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Sample records for chromium 47

  1. Chromium.

    PubMed

    Barceloux, D G

    1999-01-01

    Chromium occurs primarily in the trivalent state (III), which is the most stable form, or in the hexavalent state (VI), which is a strong oxidizing agent. Elemental chromium (0) does not occur naturally on earth. Trivalent chromium (III) is an essential trace metal necessary for the formation of glucose tolerance factor and for the metabolism of insulin. Commercial applications of chromium compounds include tanning (III), corrosion inhibition, plating, glassware-cleaning solutions, wood preservatives (VI), manufacture of safety matches, metal finishing (VI), and the production of pigments (III, VI). Hexavalent chromium (VI) contaminated local soil when chromium waste slag was part of the fill material present in residential, public, and industrial areas. In some urban areas, about two-thirds of the chromium in air results from the emission of hexavalent chromium from fossil fuel combustion and steel production. The remaining chromium in air is the trivalent form. The residence time of chromium in air is < 10 days, depending on the particle size. Trivalent compounds generally have low toxicity and the gastrointestinal tract poorly absorbs these compounds. Hexavalent chromium is a skin and mucous membrane irritant and some of these hexavalent compounds are strong corrosive agents. Hexavalent chromium compounds also produce an allergic contact dermatitis characterized by eczema. Sensitivity to trivalent compounds is much less frequent, but some workers may react to high concentrations of these compounds. Hexavalent chromium is recognized by the International Agency for Research on Cancer and by the US Toxicology Program as a pulmonary carcinogen. The increased risk of lung cancer occurs primarily in workers exposed to hexavalent chromium dust during the refining of chromite ore and the production of chromate pigments. Although individual studies suggest the possibility of an excess incidence of cancer at sites outside the lung, the results from these studies are

  2. Chromium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of chromium (Cr) on glucose and insulin metabolism are well documented. Normal dietary intake of Cr appears to be suboptimal because several studies have reported beneficial effects of Cr in people with elevated blood glucose or type 2 diabetes eating conventional diets. Stresses that ...

  3. [Biological monitoring in chromium-plating industry].

    PubMed

    Madsen, S W; Krue, S; Bonde, J P

    1992-05-25

    The purpose of the present investigation was to evaluate the role of biological monitoring as a means of surveillance of exposure in the Danish chromium-plating industry. We collected spot urine samples from 47 employees in five electro-plating plants near Aarhus and compared the results wide 40 non-exposed workers. We found no increase of chromium in urine during a work shift (mean = 0.11 nmol chromium/mmol creatinine, p = .46). The mean urine chromium value among the chromium workers was twice the mean value of the referent population (p = 0.001). There was, however, a considerable overlap between the two populations. All of the urine chromium values were much lower than the proposed American biological exposure indices. The results do not indicate any need for implementation of biological monitoring in the Danish chromium-plating industry, but longitudinal studies concerning possible accumulation of chromium at present occupational exposure levels should be carried out.

  4. Chromium - blood test

    MedlinePlus

    ... work in the following industries: Leather tanning Electroplating Steel manufacturing Decreased chromium level only occurs in people who receive all of their nutrition by vein (total parenteral nutrition or TPN) and do not get enough chromium.

  5. Chromium in diet

    MedlinePlus

    Chromium deficiency may be seen as impaired glucose tolerance. It occurs in older people with type 2 diabetes and in infants with protein-calorie malnutrition. Taking chromium supplements can help manage these conditions. However, ...

  6. Chromium adsorption by lignin

    SciTech Connect

    Lalvani, S.B.; Huebner, A.; Wiltowski, T.S.

    2000-01-01

    Hexavalent chromium is a known carcinogen, and its maximum contamination level in drinking water is determined by the US Environmental Protection Agency (EPA). Chromium in the wastewaters from plating and metal finishing, tanning, and photographic industries poses environmental problems. A commercially available lignin was used for the removal of hexavalent as well as trivalent chromium from aqueous solution. It is known that hexavalent chromium is present as an anionic species in the solution. It was found that lignin can remove up to 63% hexavalent and 100% trivalent chromium from aqueous solutions. The removal of chromium ions was also investigated using a commercially available activated carbon. This absorbent facilitated very little hexavalent and almost complete trivalent chromium removal. Adsorption isotherms and kinetics data on the metal removal by lignin and activated carbon are presented and discussed.

  7. [Chromium and insulin resistance].

    PubMed

    Kleefstra, N; Bilo, H J; Bakker, S J; Houweling, S T

    2004-01-31

    Since as early as the 50s of the last century, it has been known that chromium is essential for normal glucose metabolism. Too little chromium in the diet may lead to insulin resistance. However, there is still no standard against which chromium deficiency can be established. Nevertheless, chromium supplements are becoming increasingly popular. Various systematic reviews have been unable to demonstrate any effects of chromium on glycaemic regulation (possibly due partly to the low dosages used), but there is a slight reduction in body weight averaging 1 kg. In a double-blind randomised placebo-controlled trial in a Chinese population with type-2 diabetes mellitus, supplementation with 1000 micrograms of chromium led to a fall in the glycosylated haemoglobin level (HbA1c) by 2%. Toxic effects of chromium are seldom seen; recently, however, the safety of one of the dosage forms of chromium, chromium picolinate, has been questioned. One should be aware that individual patients with type-2 diabetes mellitus may have an increased risk of hypoglycaemic episodes when taking chromium supplements as self-medication.

  8. Sodium sulfur container with chromium/chromium oxide coating

    DOEpatents

    Ludwig, Frank A.; Higley, Lin R.

    1981-01-01

    A coating of chromium/chromium oxide is disclosed for coating the surfaces of electrically conducting components of a sodium sulfur battery. This chromium/chromium oxide coating is placed on the surfaces of the electrically conducting components of the battery which are in contact with molten polysulfide and sulfur reactants during battery operation.

  9. The carcinogenicity of chromium

    PubMed Central

    Norseth, Tor

    1981-01-01

    The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Present evidence indicates that the trivalent chromium compounds do not cause cancer although high concentrations in some in vitro systems have shown genetic toxicity. Hexavalent chromium compounds cause cancer in humans, in experimental animals and exert genetic toxicity in bacteria and in mammalian cells in vitro. Epidemiological evidence and animal experiments indicate that the slightly soluble hexavalent salts are the most potent carcinogens, but proper identification and characterization of exposure patterns in epidemiological work are lacking. Workers also tend to have mixed exposures. Soluble and slightly soluble salts are equally potent genotoxic agents in vitro. Further work for establishing dose estimates for risk evaluation in epidemiological work is important. In vitro systems should be applied for further identification of the mechanism of the carcinogenic effects, and animal experiments are urgent for comparison of the carcinogenic potency of the different hexavalent salts. Hexavalent chromium salts must be regarded as established carcinogens, and proper action should be taken in all industries with regard to such exposure. At present the carcinogenic risk to the general population caused by chromium compounds seems to be negligible, chromium in cigarettes, however, is an uncertainty in this respect. The amount of chromium and the type of chromium compounds inhaled from cigarettes is not known. PMID:7023928

  10. Bioavailability of a potato chromium complex to the laboratory rat

    SciTech Connect

    Gilbert, H.K.

    1985-01-01

    Research objectives were to study the effect of food source, preparation method and chemical form on bioavailability of chromium. Chromium concentration in potatoes was determined and tubers labeled either intrinsically or extrinsically with radioactive chromate. A labeled chromium complexes was isolated from preparations of raw, baked or fried potatoes and chromatographed on gel permeation media. Availability of the potato chromium complex to the rat was examined in three feeding studies. Animals were dosed with radioactive extrinsically or intrinsically labeled potato extract or with chromate. A labeled chromium complex was isolated from gastrointestinal contents of rats and chromatographed. Potato pulp and peel contained 1.63 and 2.70 ..mu..g Cr/g tissue respectively. True and apparent absorption from extrinsically labeled feedings were 33.4 +/- 4.7 and 29.8 +/- 11.2% respectively, and no differences existed between absorption from raw and cooked potatoes. Absorption from the extrinsic labeled potatoes differed significantly from absorption of inorganic chromatium. Apparent absorption of raw (11.1 +/- 7.9%) and cooked (-0.7 +/- 2.8%) intrinsically labeled feedings differed significantly. Absorption of inorganic chromium was 17.8% (true) and 11.5% (apparent). Examination of the chromium complex isolated from gastrointestinal tract contents showed enlargement of the complex in the stomach after consumption.

  11. Mineral of the month: chromium

    USGS Publications Warehouse

    Papp, John F.

    2005-01-01

    Chromium is one of the most indispensable industrial metals and it plays an essential but hidden role in daily life. Chromium is used in many consumer and building products, and it contributes to a clean, efficient and healthy environment.

  12. Chromium and aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aging is associated with increased blood glucose, insulin, blood lipids, and fat mass, and decreased lean body mass leading to increased incidences of diabetes and cardiovascular diseases. Improved chromium nutrition is associated with improvements in all of these variables. Insulin sensitivity de...

  13. Stabilized chromium oxide film

    DOEpatents

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  14. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L.; Nyaiesh, Ali R.

    1988-01-01

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  15. Chromium(VI)

    Integrated Risk Information System (IRIS)

    TOXICOLOGICAL REVIEW OF HEXAVALENT CHROMIUM ( CAS No . 18540 - 29 - 9 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) August 1998 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed in accordance with U.S . Environme

  16. Studies of chromium gettering

    SciTech Connect

    Simpkins, J.E.; Mioduszewski, P.; Stratton, L.W.

    1982-01-01

    Preliminary results have shown that hydrogen pumping by chromium is a surface effect. Unlike with titanium, the getter material used in many present day tokamaks, there is no significant diffusion into the bulk. Additional experiments have been carried out to measure the basic characteristics of chromium films for gases of interest in tokamak research. These gases include deuterium, oxygen and nitrogen. A vacuum system is described which allowed precise control of the test gas, a constant wall temperature and determination of the projected getter surface area. A quadrupole mass spectrometer, rather than simply a total pressure gauge, was utilized to measure the partial pressure of the test gas as well as the residual gas composition in the system. A quartz crystal monitor was used to measure film thickness. Pumping speeds and sticking coefficients are given as a function of surface coverage for each test gas. A comparison will be made with titanium films deposited in the same vacuum system and under similar conditions.

  17. Studies of chromium gettering

    NASA Astrophysics Data System (ADS)

    Simpkins, J. E.; Mioduszewski, P.; Stratton, L. W.

    1982-12-01

    Preliminary results have shown that hydrogen pumping by chromium is a surface effect. Unlike with titanium, the getter material used in many present day tokamaks, there is no significant diffusion into the bulk. This feature, which would minimize the tritium inventory, makes chromium a viable alternate to titanium gettering for future tokamaks. Additional experiments have been carried out to measure the basic characteristics of chromium films for gases of interest in tokamak research. These gases include deuterium, oxygen and nitrogen. A vacuum system is described which allowed precise control of the test gas, a constant wall temperature and determination of the projected getter surface area. A quadrupole mass spectrometer, rather than simply a total pressure gauge, was utilized to measure the partial pressure of the test gas as well as the residual gas composition in the system. A quartz crystal monitor was used to measure film thickness. Pumping speeds and sticking coefficients are given as a function of surface coverage for each test gas. A comparison will be made with titanium films deposited in the same vacuum system and under similar conditions.

  18. Anthropogenic Chromium Emissions in China from 1990 to 2009

    PubMed Central

    Cheng, Hongguang; Zhou, Tan; Li, Qian; Lu, Lu; Lin, Chunye

    2014-01-01

    An inventory of chromium emission into the atmosphere and water from anthropogenic activities in China was compiled for 1990 through to 2009. We estimate that the total emission of chromium to the atmosphere is about 1.92×105t. Coal and oil combustion were the two leading sources of chromium emission to the atmosphere in China, while the contribution of them showed opposite annual growth trend. In total, nearly 1.34×104t of chromium was discharged to water, mainly from six industrial categories in 20 years. Among them, the metal fabrication industry and the leather tanning sector were the dominant sources of chromium emissions, accounting for approximately 68.0% and 20.0% of the total emissions and representing increases of15.6% and 10.3% annually, respectively. The spatial trends of Cr emissions show significant variation based on emissions from 2005 to 2009. The emission to the atmosphere was heaviest in Hebei, Shandong, Guangdong, Zhejiang and Shanxi, whose annual emissions reached more than 1000t for the high level of coal and oil consumption. In terms of emission to water, the largest contributors were Guangdong, Jiangsu, Shandong and Zhejiang, where most of the leather production and metal manufacturing occur and these four regions accounted for nearly 47.4% of the total emission to water. PMID:24505309

  19. Chromium-induced toxic hepatitis.

    PubMed

    Lança, Sara; Alves, Amanda; Vieira, Ana Isabel; Barata, José; de Freitas, João; de Carvalho, Alvaro

    2002-12-01

    A clinical case of acute hepatitis in a patient undergoing an alternative medicine weight-reduction regimen is reported. Chromium polynicotinate had been ingested in combination with vegetable extracts over a 5-month period. Liver biopsy was compatible with toxic hepatitis and greatly elevated hepatic chromium levels were found (>10x normal). The clinical picture regressed following suspension of the medication.

  20. Groundwater contaminant by hexavalent chromium

    SciTech Connect

    Parsons, C.

    1995-11-01

    Oxidation of trivalent chromium to hexavalent chromium has been investigated as a function of total manganese in soils as well as various incubation conditions. Chromium and manganese contents were analyzed by atomic absorption (graphite furnace and flame emission respectively) following acid digestion. Total hexavalent chromium generation capacity was determined by addition of 0.001 M CrCL3, incubation, and analysis by s-diphenyl carbazide. Samples were then leached with CaSO{sub 4} and MgSO{sub 4} and incubated in various environments (oven, freeze-drier, field moist, ultrafreeze) to test for geogenic generation of Cr(IV). The degree of geogenic generation of hexavalent chromium was compared with total Mn and Cr content as well as hexavalent generational capacity.

  1. Hexavalent chromium monitor

    DOEpatents

    Tao, Shiquan; Winstead, Christopher B.

    2005-04-12

    A monitor is provided for use in measuring the concentration of hexavalent chromium in a liquid, such as water. The monitor includes a sample cell, a light source, and a photodetector. The sample cell is in the form of a liquid-core waveguide, the sample cell defining an interior core and acting as a receiver for the liquid to be analyzed, the interior surface of the sample cell having a refractive index of less than 1.33. The light source is in communication with a first end of the sample cell for emitting radiation having a wavelength of about and between 350 to 390 nm into the interior core of the waveguide. The photodetector is in communication with a second end of the waveguide for measuring the absorption of the radiation emitted by the light source by the liquid in the sample cell. The monitor may also include a processor electronically coupled to the photodetector for receipt of an absorption signal to determine the concentration of hexavalent chromium in the liquid.

  2. Chromium in metabolic and cardiovascular disease.

    PubMed

    Hummel, M; Standl, E; Schnell, O

    2007-10-01

    Chromium is an essential mineral that appears to have a beneficial role in the regulation of insulin action, metabolic syndrome, and cardiovascular disease. There is growing evidence that chromium may facilitate insulin signaling and chromium supplementation therefore may improve systemic insulin sensitivity. Tissue chromium levels of subjects with diabetes are lower than those of normal control subjects, and a correlation exists between low circulating levels of chromium and the incidence of type 2 diabetes. Controversy still exists as to the need for chromium supplementation. However, supplementation with chromium picolinate, a stable and highly bioavailable form of chromium, has been shown to reduce insulin resistance and to help reduce the risk of cardiovascular disease and type 2 diabetes. Since chromium supplementation is a safe treatment, further research is necessary to resolve the confounding data. The existing data suggest to concentrate future studies on certain forms as chromium picolinate and doses as at least 200 mcg per day.

  3. Chromium isotopes as indicators of hexavalent chromium reduction

    SciTech Connect

    Johnson, Thomas M.

    2012-03-20

    This is the final report for a university research project which advanced development of a new technology for identifying chemical reduction of hexavalent chromium contamination in groundwater systems. Reduction renders mobile and toxic hexavalent chromium immobile and less toxic. The new method uses stable isotope ratio measurements, which are made using multicollector ICP-mass spectrometry. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.

  4. Is chromium pharmacologically relevant?

    PubMed

    Vincent, John B

    2014-10-01

    Recent research, combined with reanalysis of previous results, has revealed that chromium can no longer be considered an essential trace element. Clinical studies are ambiguous at best as to whether Cr has a pharmacological effect in humans. Observed effects of Cr on rodent models of insulin resistance and diabetes are best interpreted in terms of a pharmacological role for Cr. Studies on the effects of Cr on rat models of diabetes are reviewed herein and suggest Cr increases insulin sensitivity in peripheral tissues of the rodent models. The lack of effects in human studies may stem from humans receiving a comparably smaller dose than the rodent models. However, given the different responses to Cr in the rodent models, humans could potentially have different responses to Cr.

  5. Evaluation of aquatic toxicities of chromium and chromium-containing effluents in reference to chromium electroplating industries.

    PubMed

    Baral, A; Engelken, R; Stephens, W; Farris, J; Hannigan, R

    2006-05-01

    This study evaluated aquatic toxicities of chromium and chromium-containing laboratory samples representative of effluents from chromium electroplating industries, and compared the aquatic environmental risks of hexavalent and trivalent chromium electroplating operations. Trivalent chromium electroplating has emerged as an acceptable alternative to hazardous hexavalent chromium electroplating. This process substitution has reduced the human health impact in the workplace and minimized the production of hazardous sludge regulated under the Resource Conservation and Recovery Act (RCRA). The thrust behind this research was to investigate whether trivalent chromium electroplating operations have lower adverse impacts on standardized toxicity test organisms. Ceriodaphnia dubia and Pimephales promelas were used to investigate toxicities of trivalent chromium (Cr (III)), hexavalent chromium (Cr (VI)), and industrial effluents. In agreement with previous studies, Cr (III) was found to be less toxic than Cr (VI). Despite having several organic and inorganic constituents in the effluents obtained from trivalent chromium plating baths, they exhibited less adverse effects to C. dubia than effluents obtained from hexavalent chromium electroplating baths. Thus, transition from hexavalent to trivalent chromium electroplating processes may be justified. However, because of the presence of organic constituents such as formate, oxalate, and triethylene glycol in effluents, trivalent chromium electroplating operations may face additional regulatory requirements for removal of total organic carbon.

  6. Chromium deficiency during total parenteral nutrition.

    PubMed

    Freund, H; Atamian, S; Fischer, J E

    1979-02-02

    Chromium is required for maintenance of normal glucose tolerance. After complete bowel resection and five months of total parenteral nutrition, severe glucose intolerance, weight loss, and a metabolic encephalopathy-like confusional state developed in a patient. Serum chromium levels were at the lowest normal level. Supplementation of 150 microgram of chromium per day reversed the glucose intolerance, reduced insulin requirements, and resulted in weight gain and the disappearance of encephalopathy. The low levels of chromium and response to chromium supplementation suggest that chromium deficiency can arise in long-term total parenteral nutrition.

  7. The contemporary anthropogenic chromium cycle.

    PubMed

    Johnson, Jeremiah; Schewel, Laura; Graedel, T E

    2006-11-15

    Chromium is an essential engineering metal used in stainless and alloy steels, chemicals, and refractory products. Using material flow analysis, all major anthropogenic chromium flows are characterized for the year 2000, from mining through discard, on three spatial levels: fifty-four countries, nine world regions, and the planet. Included is the first detailed quantification of chromium in internationally traded finished products and diverse waste streams. Findings include (1) 78% of chromium flow entering final use is added as a net addition to stock on the global level; most countries are close to this figure; (2) the majority of mining occurs in Africa (2400 Gg Cr/yr) and the Commonwealth of Independent States (1090 Gg Cr/yr), while the major end-users are Asia, Europe, and North America at 1150, 1140, and 751 Gg Cr/yr, respectively; (3) waste flows of chromium are the greatest in Europe (420 Gg Cr/yr), Asia (370 Gg Cr/yr), and North America (290 Gg Cr/yr), but the composition of these waste flows varies greatly among the world regions; (4) releases of chromium by the global system, which total 2630 Gg Cr/yr, are nearly evenly divided among tailings, ferrochromium slag, downgraded scrap, and post-consumer losses; (5) many countries have a heavy foreign dependence on chromium in the all forms, as is demonstrated for the United States. The findings relating to in-use stock changes and finished product trade are relevant to industry, allowing for more accurate planning for future scrap availability. The quantification of releases due to discards and dissipation hold environmental and human health relevance, while the full life cycle international trade assessment addresses local scarcity.

  8. Antiferromagnetism in chromium

    NASA Astrophysics Data System (ADS)

    Jaramillo, Rafael

    I present two experimental studies of the spin density wave antiferromagnetic order in elemental Chromium. The first addresses the response of the magnetic ground state to applied pressure. The spin and charge order parameters are probed at high pressure and low temperature in a diamond anvil cell using monochromatic X-ray diffraction. We find that the magnetism is suppressed exponentially with pressure, providing a canonical example of a weak-coupling, mean-field ground state, before terminating at a quantum phase transition. We confirm the harmonic relationship between the spin and charge degrees of freedom in the low temperature regime, and we identify the microscopic coupling between pressure and magnetism. The discovery of the long-sought-after quantum critical regime sets the stage for a complete study of antiferromagnetic quantum criticality in this clean model system. The second study addresses the thermodynamics and transport properties of antiferromagnetic domain structure. We find a robust thermal hysteresis in the longitudinal and Hall resistivities of sub-mm bulk Cr samples. The temperature limits of the hysteresis are correlated with domain wall fluctuations and freezing. The persistent sign of the hysteresis and the macroscopic return point memory warrant a new understanding of domain wall energetics. By combining electrical transport and X-ray microdiffraction measurements we are able to pinpoint the effects of antiferromagnetic domain walls on electron transport.

  9. Mare Chromium Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This crater, located in Mare Chromium, shows evidence of exterior modification, with little interior modification. While the rim is still visible, the ejecta blanket has been removed or covered. There is some material at the bottom of the crater, but the interior retains the bowl shape from the initial formation of the crater.

    Image information: VIS instrument. Latitude -34.4, Longitude 174.4 East (185.6 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Chromium-induced kidney disease

    SciTech Connect

    Wedeen, R.P. ); Qian, Lifen )

    1991-05-01

    Kidney disease is often cited as one of the adverse effects of chromium, yet chronic renal disease due to occupational or environmental exposure to chromium has not been reported. Occasional cases of acute tubular necrosis (ATN) following massive absorption of chromate have been described. Chromate-induced ATN has been extensively studied in experimental animals following parenteral administration of large doses of potassium chromate (hexavalent). The chromate is selectively accumulated in the convoluted proximal tubule where necrosis occurs. An adverse long-term effect of low-dose chromium exposure on the kidneys is suggested by reports of low molecular weight (LMW) proteinuria in chromium workers. Excessive urinary excretion of {beta}{sub 2}-microglobulin, a specific proximal tubule brush border protein, and retinol-binding protein has been reported among chrome palters and welders. However, LMW proteinuria occurs after a variety of physiologic stresses, is usually reversible, and cannot by itself be considered evidence of chromic renal disease. Chromate-induced ATN and LMW proteinuria in chromium workers, nevertheless, raise the possibility that low-level, long-term exposure may produce persistent renal injury. The absence of evidence of chromate-induced chromic renal disease cannot be interpreted as evidence of the absence of such injury.

  11. Diffusion of Chromium in Alpha Cobalt-Chromium Solid Solutions

    NASA Technical Reports Server (NTRS)

    Weeton, John W

    1951-01-01

    Diffusion of chromium in cobalt-chromium solid solutions was investigated in the range 0 to 40 atomic percent at temperatures of 1360 degrees, 1300 degrees, 1150 degrees, and 10000 degrees c. The diffusion coefficients were found to be relatively constant within the composition range covered by each specimen. The activation heat of diffusion was determined to be 63,000 calories per mole. This value agrees closely with the value of 63,400 calories per mole calculated by means of the Dushman-Langmuir equation.

  12. Precipitating Chromium Impurities in Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Salama, A. M.

    1982-01-01

    Two new treatments for silicon wafers improve solar-cell conversion efficiency by precipitating electrically-active chromium impurities. One method is simple heat treatment. Other involves laser-induced damage followed by similar heat treatment. Chromium is one impurity of concern in metallurgical-grade silicon for solar cells. In new treatment, chromium active centers are made electrically inactive by precipitating chromium from solid solution, enabling use of lower grade, lower cost silicon in cell manufacture.

  13. Chromium at High Pressure

    NASA Astrophysics Data System (ADS)

    Jaramillo, Rafael

    2012-02-01

    Chromium has long served as the archetype of spin density wave magnetism. Recently, Jaramillo and collaborators have shown that Cr also serves as an archetype of magnetic quantum criticality. Using a combination of x-ray diffraction and electrical transport measurements at high pressures and cryogenic temperatures in a diamond anvil cell, they have demonstrated that the N'eel transition (TN) can be continuously suppressed to zero, with no sign of a concurrent structural transition. The order parameter undergoes a broad regime of exponential suppression, consistent with the weak coupling paradigm, before deviating from a BCS-like ground state within a narrow but accessible quantum critical regime. The quantum criticality is characterized by mean field scaling of TN and non mean field scaling of the transport coefficients, which points to a fluctuation-induced reconstruction of the critical Fermi surface. A comparison between pressure and chemical doping as means to suppress TN sheds light on different routes to the quantum critical point and the relevance of Fermi surface nesting and disorder at this quantum phase transition. The work by Jaramillo et al. is broadly relevant to the study of magnetic quantum criticality in a physically pure and theoretically tractable system that balances elements of weak and strong coupling. [4pt] [1] R. Jaramillo, Y. Feng, J. Wang & T. F. Rosenbaum. Signatures of quantum criticality in pure Cr at high pressure. Proc. Natl. Acad. Sci. USA 107, 13631 (2010). [0pt] [2] R. Jaramillo, Y. Feng, J. C. Lang, Z. Islam, G. Srajer, P. B. Littlewood, D. B. McWhan & T. F. Rosenbaum. Breakdown of the Bardeen-Cooper-Schrieffer ground state at a quantum phase transition. Nature 459, 405 (2009).

  14. Environmental biochemistry of chromium.

    PubMed

    Losi, M E; Amrhein, C; Frankenberger, W T

    1994-01-01

    Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming

  15. Chromium-51 calibrating neutrino source

    SciTech Connect

    Demchenko, N.F.; Karasev, V.I.; Karelin, E.A.

    1993-12-31

    The problem for measurement of the sun neutrino flux is resolved at the specially made Baksansk neutrino telescope and calls for calibration of registration system. For this a man made neutrino source is required with the known yield of particles and intensity comparable with the intensity of the measured subject. The most suitable radionuclide for production of this source is chromium-51 the radionuclide decay of which is accompanied with neutrino radiation. At the Research Institute of Atomic Reactors (in Dimitrovgrad) the production technology is developed as well as the closed chromium-51 neutrino source is made of 4 x 10{sup 5} Ci activity. The parts of active source made in the form of core of metallic isotope-enriched chromium were irradiated in the high flux neutron trap of the SM-2 reactor. The sources were subsequently assembled at the shield cells with remote equipment application. The source was certificated as a special form radioactive material. Due to low half-life of chromium-51 (T 1/2 - 27 hours) all the operations on assembly, certification and delivery of source to the Baksansk Laboratory were performed at the earliest possible date (less than 3 days).

  16. Chromium(III), insoluble salts

    Integrated Risk Information System (IRIS)

    TOXICOLOGICAL REVIEW OF TRIVALENT CHROMIUM ( CAS No . 16065 - 83 - 1 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) August 1998 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed in accordance with U.S . Environmen

  17. Modeling of chromium in ground water

    SciTech Connect

    Shen, Huiying; Nikolaidis, N.P.

    1995-12-01

    National Chromium is a metal-plating facility located in Putnam, Connecticut that has been in operation for 55 years. Chromium has dripped onto the wooden floor and leached into the groundwater. The process that affect the fate and transport of chromium in groundwater are aqueous complexation, adsorption/desorption, precipitation/dissolution, and solute transport. In addition, field data and laboratory studies using soil samples from this site indicate that a predominant retardation process is diffusion into the soil matrix. While aqueous complexation usually takes seconds or less, the time scales of chromium diffusion in soil matrix is years. A three-dimensional multicomponent solute transport model has been developed to study the fate, speciation and transport of chromium. The model has been applied to the National Chromium site in a hind casting to study (1) the interaction among the processes, (2) the implication of chromium diffusion in soil matrix on remediation technologies, and (3) the time scales of remediation.

  18. Chromium in the environment of Finland.

    PubMed

    Mukherjee, A B

    1998-06-30

    This paper focuses upon the use, import and release of chromium to the environment of Finland. In addition, the behavior of trivalent and hexavalent chromium in soils has been briefly reviewed. In Finland, consumption of chromium compounds occurs in the following pattern: stainless steel > leather tanning > metal plating > chemicals. The emission of chromium has decreased from 114 t in 1979 to 28 t in 1995. The highest release of chromium continues to be from ferrochromium and stainless steel plants. From these facilities, 85% of slag and dusts are used by a secondary facility to recover valuable metal. In the industrial areas, the oxidizing behavior of chromium (III) is still unknown. In this study, the leachability of chromium (VI) to ground water and its effects on terrestrial and aquatic species in Finland are discussed.

  19. [Worldwide cancer mortality among chromium platers].

    PubMed

    Hara, Toshiyuki; Takahashi, Ken

    2012-12-01

    The elevated risk of lung cancer among chromate-producing workers has been confirmed by many epidemiological studies. Although chromium has been most used in the chromium plating industry and many platers are employed in small-scale factories, cancer studies have been documented in only a few investigations. We have conducted several prospective cohort studies in Japanese chromium platers and recently extended them through 2003. We additionally surveyed epidemiological studies among chromium platers carried out in other parts of the world. Occupational chromium exposure through chromium plating work may be a risk factor for mortality not only from lung cancer but also malignant lymphoma and brain tumor. The age at first exposure to chromium may be a more important factor than the duration of exposure for an increased risk of lung cancer and malignant lymphoma.

  20. The use of trivalent chromium bath to obtain a solar selective black chromium coating

    NASA Astrophysics Data System (ADS)

    Survilienė, S.; Češūnienė, A.; Juškėnas, R.; Selskienė, A.; Bučinskienė, D.; Kalinauskas, P.; Juškevičius, K.; Jurevičiūtė, I.

    2014-06-01

    Black chromium coatings were electrodeposited from a trivalent chromium bath using a ZnO additive as a second main component. Black chromium was electrodeposited on steel and copper plates and substrates plated with bright nickel prior to black chromium electrodeposition. The black chromium coatings were characterized by XRD and SEM. The XRD data suggest that the phase structure of black chromium may be defined as a zinc solid solution in chromium or a chromium solid solution in zinc depending on the chromium/zinc ratio in the deposit. The role of substrate finish was evaluated through the corrosion resistance and reflectance of black chromium. According to corrosion tests the samples plated with bright nickel prior to black chromium deposition have shown the highest corrosion resistance. The electrodeposited black chromium possesses good optical properties for the absorption of solar energy. The absorption coefficient of black chromium was found to be over 0.99 for the samples obtained without the Ni undercoat and below 0.99 for those obtained with the use of Ni undercoat. However, the use of nickel undercoat before black chromium plating is recommended because it remarkably improves the corrosion resistance of samples.

  1. Remediation of soils contaminated with chromium using citric and hydrochloric acids: the role of chromium fractionation in chromium leaching.

    PubMed

    Cheng, Shu-Fen; Huang, Chin-Yuan; Tu, Yao-Ting

    2011-01-01

    Acid washing is a common method for soil remediation, but is not always efficient for chromium-contaminated soil. Both soil particle size and the forms of chromium existing in the soil affect the efficiency of soil washing. Laboratory batch and column dissolution experiments were conducted to determine the efficiencies of citric and hydrochloric acids as agents to extract chromium from soils contaminated with chromium. The effects of soil particle size and chromium fractionation on Cr leaching were also investigated. About 90% of chromium in the studied soil existed either in residual form or bound to iron and manganese oxides, and Cr fraction distributions were similar for all soil particle sizes. Almost all exchangeable and carbonate-bound chromium was removed by washing once with 0.5 M HCl, whereas organic chromium was more effectively removed by washing with citric acid rather than with HCl solution of the same concentration. For chromium fractions that were either bound to Fe-Mn oxides or existed as residual forms, the efficiencies of acid washing were usually 20% or less, except for 0.5 M HCl solution, which had much higher efficiencies. Separation of the soil sample by particle size before the separate washing of the soil fractions had little improvement on the chromium removal.

  2. Atmospheric releases of hexavalent chromium from hard chromium plating operations

    SciTech Connect

    Hall, M.S.; Dietz, J.D.; Cooper, C.D.; Wayson, R.L.; Bauman, D.

    1992-01-01

    The study represents an assessment of airborne fugitive hexavalent chromium concentrations at these facilities. In an effort to develop a model for stack emissions of Cr(VI), EPA data were reviewed and a correlation for chromium emissions was reported versus ampere-hours and plating bath volume. A modification of a stack sampling train was constructed to accommodate fugitive sampling efforts made at two hard chrome plating facilities. The levels found at both sites, for the most part, were below detection limits of 4 micrograms cu m and 6 micrograms cu m for the 1st and 2nd plant, respectively. The annual emission rates from Plants 1 and 2 are < 0.5 and < 1 lb Cr(VI) per year, respectively.

  3. Electrodeposition of cobalt-chromium alloy from trivalent chromium solutions

    SciTech Connect

    Dasarathy, H.; Riley, C.; Coble, H.D. . Dept. of Chemistry and Materials Science)

    1994-07-01

    Cobalt-chromium alloy was deposited from plating solutions containing cobalt(II) chloride and chromium(III) chloride at 3.5 pH. The deposits were obtained using both single and mixed complex solutions. Deposit morphology showed significant dependence on the complexing agent(s) used. Partitioning of the two components in the deposit as determined by energy dispersive spectroscopy depended on plating parameters such as concentration ratio of the two salts in the solution, complexing agent, type of current (both dc and pulsed current were studied), and current density. X-ray photoelectron spectroscopy spectra collected from as-deposited alloy revealed the presence of both oxides and metals. X-ray diffraction spectra for the alloy deposit indicated solid solution formation.

  4. Occurrences, uses, and properties of chromium.

    PubMed

    Barnhart, J

    1997-08-01

    Chromium is the 21st most abundant element in the Earth's crust with a mean concentration in United States soils of about 40 mg/kg. Although it exists in several oxidation states, the zero, trivalent, and hexavalent states are the most important in commercial products and the environment. Nearly all naturally occurring chromium is in the trivalent state, usually in combination with iron or other metal oxides. Although only about 15% of the chromium mined is used in the manufacture of chemicals, most applications of chromium utilize the chemistry of chromium. For instance, the "stainless" nature of stainless steel is due to the chemical properties of the chromium oxides which form on the surface of the alloy. Similarly, the protective properties of chrome plating of metals, chromated copper arsenate (CCA) treatment of wood, and chrome tanning of leather are all dependent on chromium chemistry. The key to these uses is that under typical environmental and biological conditions of pH and oxidation-reduction potential, the most stable form of chromium is the trivalent oxide. This form has very low solubility and low reactivity resulting in low mobility in the environment and low toxicity in living organisms. In this paper the chemical properties of chromium are discussed for the major commercial products in the context of the Eh-pH diagram for chromium.

  5. Food Chromium Contents, Chromium Dietary Intakes And Related Biological Variables In French Free-Living Elderly

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chromium (Cr III), an essential trace element, functions in potentiating insulin sensitivity, regulating glucose homeostasis, improving lipid profile, and maintaining lean body mass. Glucose intolerance and chromium deficiency increase with age, and could be aggravating factors of the metabolic synd...

  6. Sonoassisted microbial reduction of chromium.

    PubMed

    Kathiravan, Mathur Nadarajan; Karthick, Ramalingam; Muthu, Naggapan; Muthukumar, Karuppan; Velan, Manickam

    2010-04-01

    This study presents sonoassisted microbial reduction of hexavalent chromium (Cr(VI)) using Bacillus sp. isolated from tannery effluent contaminated site. The experiments were carried out with free cells in the presence and absence of ultrasound. The optimum pH and temperature for the reduction of Cr(VI) by Bacillus sp. were found to be 7.0 and 37 degrees C, respectively. The Cr(VI) reduction was significantly influenced by the electron donors and among the various electron donors studied, glucose offered maximum reduction. The ultrasound-irradiated reduction of Cr(VI) with Bacillus sp. showed efficient Cr(VI) reduction. The percent reduction was found to increase with an increase in biomass concentration and decrease with an increase in initial concentration. The changes in the functional groups of Bacillus sp., before and after chromium reduction were observed with FTIR spectra. Microbial growth was described with Monod and Andrews model and best fit was observed with Andrews model.

  7. Welding of high chromium steels

    NASA Technical Reports Server (NTRS)

    Miller, W B

    1928-01-01

    A brief description is given of different groups of high chromium steels (rustless iron and stainless steels) according to their composition and more generally accepted names. The welding procedure for a given group will be much the same regardless of the slight variations in chemical composition which may exist within a certain group. Information is given for the tensile properties (yield point and ultimate strength) of metal sheets and welds before and after annealing on coupons one and one-half inches wide. Since welds in rustless iron containing 16 to 18 percent chromium and 7 to 12 percent nickel show the best combination of strength and ductility in the 'as welded' or annealed condition, it is considered the best alloy to use for welded construction.

  8. Assessing model uncertainty using hexavalent chromium and ...

    EPA Pesticide Factsheets

    Introduction: The National Research Council recommended quantitative evaluation of uncertainty in effect estimates for risk assessment. This analysis considers uncertainty across model forms and model parameterizations with hexavalent chromium [Cr(VI)] and lung cancer mortality as an example. The objective of this analysis is to characterize model uncertainty by evaluating the variance in estimates across several epidemiologic analyses.Methods: This analysis compared 7 publications analyzing two different chromate production sites in Ohio and Maryland. The Ohio cohort consisted of 482 workers employed from 1940-72, while the Maryland site employed 2,357 workers from 1950-74. Cox and Poisson models were the only model forms considered by study authors to assess the effect of Cr(VI) on lung cancer mortality. All models adjusted for smoking and included a 5-year exposure lag, however other latency periods and model covariates such as age and race were considered. Published effect estimates were standardized to the same units and normalized by their variances to produce a standardized metric to compare variability in estimates across and within model forms. A total of 7 similarly parameterized analyses were considered across model forms, and 23 analyses with alternative parameterizations were considered within model form (14 Cox; 9 Poisson). Results: Across Cox and Poisson model forms, adjusted cumulative exposure coefficients for 7 similar analyses ranged from 2.47

  9. Nasal manifestations in chromium industry workers.

    PubMed

    Aiyer, R G; Kumar, Gaurav

    2003-04-01

    People working in mines, plating factories, cement industries are mainly exposed to chrome substances, IIexavalent chromium has been implicated for its toxic effect on the nasal mucosa. Hereby we present a rare study of 28 patients who attended out patient department of Otorhinolaryngology at SSG Hospital, Baroda from a nearby chromium industry. This study aims to present various nasal manifestations of toxic effects of prolonged chromium exposure.

  10. Bendability of aluminiumand steel-clad chromium plates

    NASA Astrophysics Data System (ADS)

    Yoshida, Fusahito; Okada, Tatsuo; Itoh, Misao; Harada, Yasunori; Ohmori, Masanobu

    1998-05-01

    The present paper describes how the cladding of chromium plate with dissimilar metals improves the plastic bendability of the chromium. Three-point bending tests at various temperatures were performed for three types of chromium specimens: a monolithic chromium plate, aluminium- and steel-clad chromium plate. The aluminium-clad chromium plate was bent at 343 K up to a bent angle of 90 degrees without failure, even when the chromium layer was located outside of the plate (tension side), while the monolithic chromium plate could be bent exclusively at temperatures above 403 K. When the chromium layer was located inside of the steel-clad chromium plate (compression side), the plate was successfully bent at 307 K. The FE stress analysis of bending proved that the cladding of chromium plates with proper metals of different kinds is effective to reduce the tensile stress in chromium induced during bending and also the residual stress existing after bending operation.

  11. Removal of hexavalent chromium using distillery sludge.

    PubMed

    Selvaraj, K; Manonmani, S; Pattabhi, S

    2003-09-01

    Batch mode experiments were conducted to study the removal of hexavalent chromium from aqueous and industrial effluent using distillery sludge. Effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(VI) were studied. The data obeyed Langmuir and Freundlich adsorption isotherms. The Langmuir adsorption capacity was found to be 5.7 mg/g. Freundlich constants K(f) and n were 2.05 [mg/g(L/mg)(n)] and 3.9, respectively. Desorption studies indicated the removal of 82% of the hexavalent chromium. The efficiency of adsorbent towards the removal of chromium was also tested using chromium-plating wastewater.

  12. [Chromium exposure biological indices and clinical findings in chromium plating industry (author's transl)].

    PubMed

    Franchini, I; Cavatorta, A; Mutti, A; Marcato, M; Bottazzi, D; Cigala, F

    1977-09-01

    According to the investigations carried out on workers of two chromium plating plants, the authors believe that chromium urinary excretion allows to determine the degree of its acute absorption. Moreover, the renal clearance of diffusible chromium allows the evaluation of chromium body burden and is related to the duration as well as to the severity of exposure. This interpretation is supported by the relation between the exposure biological indexes and the clinical and instrumental investigations which make possible the evaluation of lesions caused by chromium exposure, mostly concerning the respiratory system.

  13. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    SciTech Connect

    Smith, W.H.; Purdy, G.M.

    1995-12-31

    This study was undertaken to determine if chromium(+6) could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium(+3) to chromium(+6) by nitric acid; and the reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium(+3) to chromium(+6) was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the (+6) oxidation state and would not exist in the (+6) state in the final process waste solutions.

  14. REACTIVE SPUTTER DEPOSITION OF CHROMIUM NITRIDE COATINGS

    EPA Science Inventory

    The effect of substrate temperature and sputtering gas compositon on the structure and properties of chromium-chromium nitride films deposited on C-1040 steel using r.f. magnetron sputter deposition was investigated. X-ray diffraction analysis was used to determine the structure ...

  15. Environmental Durability of Electroplated Black Chromium

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1983-01-01

    Report describes tests of durability of electroplated black chromium coatings on solar-collector panels in rural, industrial, and seacoast environments for 60, 36, and 13 months, respectively. Black-chromium coating showed exceptionally-good optical durability in all three environments.

  16. [Bioremediation of chromium (VI) contaminated site by reduction and microbial stabilization of chromium].

    PubMed

    Zheng, Jia-Chuan; Zhang, Jian-Rong; Liu, Xi-Wen; Xu, Qian; Shi, Wei-Lin

    2014-10-01

    Chromium (VI) contaminated soil samples were collected from a chemical plant in Suzhou. Firstly, the reduced soil was prepared by adding reagent (Stone-sulfure reagent) into polluted soil to transfer most chromium (VI) into chromium (III), then a nutrient solution was introduced into the reduced soil, and the stabilized soil was obtained after 60 days culturing. The chromium (VI) content of the three kinds of soil was analyzed. The results showed that the chromium (VI) content in toxicity characteristic leaching liquid (TCLL) dropped by 96. 8% (from 8.26 mg · L(-1) to 0.26 mg · L(-1)), and the total chromium content dropped by 95.7% (from 14.66 mg · L(-1) to 0.63 mg · L(-1)) after bioremediation in 5% nutrient solution. Additionally, the durability of chromium stabilization was tested by potassium permanganate oxidation and sterilization of microbe-treated soil. After oxidation, the chromium (VI) content in TCLL of the reduced soil was increased from 8.26 mg · L(-1) to 14.68 mg · L(-1). However, the content after bioremediation was decreased to 2.68 mg · L(-1). The results of sterilization demonstrated that the death of microbe had no significant effect on the stabilization of chromium. Consequently, the research in this paper demonstrated the feasibility of bioremediation of chromium (VI) polluted soil through reduction followed by stabilization/soilidification, and provided a technique with low cost but high efficiency.

  17. Low-chromium reduced-activation chromium-tungsten steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.; Maziasz, P.J.

    1996-10-01

    Bainitic microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of non-classical bainite were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was found to be considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2 1/4Cr-2W and 2 1/4Cr-2WV steel compositions to increase their hardenability, and the microstructures and mechanical properties were examined.

  18. [Examination of nickel and chromium contents in selected herbs, herbal fruit teas and their infusions].

    PubMed

    Błoniarz, Jadwiga; Zareba, Stanisław; Rahnama, Mansur

    2004-01-01

    The aim of this study was to determine the contents of nickel and chromium (the trace elements that are necessary for the human organism only in specified amounts) in selected dry herbs, herbal-fruit teas and their water extracts. This examination was expected to answer the question whether infusions or decoctions may constitute the additional source of these elements, or whether the amounts of nickel and chromium included in them may be dangerous for the human organism. The samples were dry mineralized at the temperature of 450 degrees C. Atomic absorption spectrometry (AAS) was performed using SOLAAR M5 appliance produced by a US-based Thermo Elemental company; nickel contents were determined from the organic phase, and chromium directly from the mineralisate. Nickel contents ranged on average from 0.56 microg/g to 2.68 microg/g in herbs and from 0.99 microg/g to 1.70 microg/g in herbal fruit teas. On average 40.0% to 82.5% of the amount present in dry, raw material passed into the infusions. The determined amounts of chromium ranged from 0.57 microg/g to 1.36 microg/g in herbs, and from 0.47 microg/g to 1.17 microg/g in herbal fruit teas (average values). The maximum extraction of this element into the infusion or decoction equaled 85.0%. The contents of nickel and chromium in the examined dry herb samples were comparable to results obtained by authors of the other papers. Infusions or decoctions of the examined herbs and herbal fruit teas contain the amounts of these elements that do not harm health and may constitute an additional source of nickel and chromium for the human organism.

  19. Chromium is not an essential trace element for mammals: effects of a "low-chromium" diet.

    PubMed

    Di Bona, Kristin R; Love, Sharifa; Rhodes, Nicholas R; McAdory, DeAna; Sinha, Sarmistha Halder; Kern, Naomi; Kent, Julia; Strickland, Jessyln; Wilson, Austin; Beaird, Janis; Ramage, James; Rasco, Jane F; Vincent, John B

    2011-03-01

    Chromium was proposed to be an essential trace element over 50 years ago and has been accepted as an essential element for over 30 years. However, the studies on which chromium's status are based are methodologically flawed. Whether chromium is an essential element has been examined for the first time in carefully controlled metal-free conditions using a series of purified diets containing various chromium contents. Male Zucker lean rats were housed in specially designed metal-free cages for 6 months and fed the AIN-93G diet with no added chromium in the mineral mix component of the diet, the standard AIN-93G diet, the standard AIN-93G diet supplemented with 200 μg Cr/kg, or the standard AIN-93G diet supplemented with 1,000 μg Cr/kg. The chromium content of the diet had no effect on body mass or food intake. Similarly, the chromium content of the diet had no effect on glucose levels in glucose tolerance or insulin tolerance tests. However, a distinct trend toward lower insulin levels under the curve after a glucose challenge was observed with increasing chromium content in the diet; rats on the supplemented AIN-93G diets had significantly lower areas (P < 0.05) than rats on the low-chromium diet. The studies reveal that a diet with as little chromium as reasonably possible had no effect on body composition, glucose metabolism, or insulin sensitivity compared with a chromium-"sufficient" diet. Together with the results of other recent studies, these results clearly indicate that chromium can no longer be considered an essential element.

  20. Potentiometry: A Chromium (III) -- EDTA Complex

    ERIC Educational Resources Information Center

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  1. Efficiency of silicon solar cells containing chromium

    DOEpatents

    Frosch, Robert A. Administrator of the National Aeronautics and Space; Salama, Amal M.

    1982-01-01

    Efficiency of silicon solar cells containing about 10.sup.15 atoms/cm.sup.3 of chromium is improved about 26% by thermal annealing of the silicon wafer at a temperature of 200.degree. C. to form chromium precipitates having a diameter of less than 1 Angstrom. Further improvement in efficiency is achieved by scribing laser lines onto the back surface of the wafer at a spacing of at least 0.5 mm and at a depth of less than 13 micrometers to preferentially precipitate chromium near the back surface and away from the junction region of the device. This provides an economical way to improve the deleterious effects of chromium, one of the impurities present in metallurgical grade silicon material.

  2. Efficiency of silicon solar cells containing chromium

    NASA Technical Reports Server (NTRS)

    Salama, A. M. (Inventor)

    1982-01-01

    Efficiency of silicon solar cells containing about one quadrillon atoms cu cm of chromium is improved about 26% by thermal annealing of the silicon wafer at a temperature of 200 C to form chromium precipitates having a diameter of less than 1 Angstrom. Further improvement in efficiency is achieved by scribing laser lines onto the back surface of the wafer at a spacing of at least 0.5 mm and at a depth of less than 13 micrometers to preferentially precipitate chromium near the back surface and away from the junction region of the device. This provides an economical way to improve the deleterious effects of chromium, one of the impurities present in metallurgical grade silicon mateial.

  3. OPTIMIZATION AND EVALUATION OF CHROMIUM COMPOSITES.

    DTIC Science & Technology

    COMPOSITE MATERIALS), (*CHROMIUM ALLOYS , POWDER METALLURGY, REINFORCING MATERIALS, TANTALUM ALLOYS , CARBON ALLOYS , OPTIMIZATION, TENSILE PROPERTIES...FRACTOGRAPHY, RUPTURE, DUCTILITY, CORROSION, EROSION, THERMOCOUPLES, PROTECTIVE COVERINGS, FLUIDICS, JET ENGINES, MAGNESIUM COMPOUNDS, OXIDES, VANADIUM ALLOYS , SILICON ALLOYS .

  4. Attenuation of chromium toxicity by bioremediation technology.

    PubMed

    Mohanty, Monalisa; Patra, Hemanta Kumar

    2011-01-01

    Chromium is an important toxic environmental pollutant. Chromium pollution results largely from industrial activities, but other natural and anthropogenic sources also contribute to the problem. Plants that are exposed to environmental contamination by chromium are affected in diverse ways, including a tendency to suffer metabolic stress. The stress imposed by Cr exposure also extends to oxidative metabolic stress in plants that leads to the generation of active toxic oxygen free radicals. Such active free radicals degrade essential biomolecules and distort plant biological membranes. In this chapter, we describe sources of environmental chromium contamination, and provide information about the toxic impact of chromium on plant growth and metabolism. In addition, we address different phytoremediation processes that are being studied for use worldwide, in contaminated regions, to address and mitigate Cr pollution. There has been a long history of attempts to successfully mitigate the toxic effects of chromium-contaminated soil on plants and other organisms. One common approach, the shifting of polluted soil to landfills, is expensive and imposes environmental risks and health hazards of its own. Therefore, alternative eco-friendly bioremediation approaches are much in demand for cleaning chromium-polluted areas. To achieve its cleaning effects, bioremediation utilizes living organisms (bacteria, algae, fungi, and plants) that are capable of absorbing and processing chromium residues in ways which amend or eliminate it. Phytoremediation (bioremediation with plants) techniques are increasingly being used to reduce heavy metal contamination and to minimize the hazards of heavy metal toxicity. To achieve this, several processes, viz., rhizofiltration, phytoextraction, phytodetoxification, phytostabilization, and phytovolatilization, have been developed and are showing utility in practice, or promise. Sources of new native hyperaccumulator plants for use at contaminated

  5. Trivalent chromium, in atherosclerosis and diabetes.

    PubMed

    Mossop, R T

    1991-11-01

    The known effects of trivalent chromium (Cr) in lowering blood levels of low density lipoproteins (LDL), raising high density lipoproteins (HDL) and improving glucose tolerance are summarised. Chromium deficiency cannot easily be established by direct means, but can be inferred by the reversal of symptoms and signs following the administration of trivalent chromium. This evidence can be supported by knowledge or suspicion of a deficiency in the diet, common in those who use highly refined cereal foods. It is considered that the beneficial effects of chromium repletion are now so well established and the trivalent form is so free of toxicity that it should now be used in clinical medicine for the benefit of those with some forms of diabetes and its complications and those suffering from atherosclerosis. Of perhaps more importance is the public health aspect, since most chromium is discarded in the cereal refinement process, we now have added evidence for a return to the diets in which complex carbohydrates predominated. In those who refuse or are unable to do this, possibly the addition of chromium to their drinking water may be of value.

  6. Bioremediation of chromium solutions and chromium containing wastewaters.

    PubMed

    Malaviya, Piyush; Singh, Asha

    2016-08-01

    Cr(VI) represents a serious threat to human health, living resources and ecological system as it is persistent, carcinogenic and toxic, whereas, Cr(III), another stable oxidation state of Cr, is less toxic and can be readily precipitated out of solution. The conventional methods of Cr(VI) removal from wastewaters comprise of chemical reduction followed by chemical precipitation. However, these methods utilize large amounts of chemicals and generate toxic sludge. This necessitates the need for devising an eco-technological strategy that would use the untapped potential of the biological world for remediation of Cr(VI) containing wastewaters. Among several viable approaches, biotransformation of Cr(VI) to relatively non-toxic Cr(III) by chromium resistant bacteria offers an economical- and environment-friendly option for its detoxification. Various studies on use of Cr(VI) tolerant viable bacterial isolates for treatment of Cr(VI) containing solutions and wastewater have been reported. Therefore, a detailed account of mechanisms and processes involved in bioreduction of Cr(VI) from solutions and wastewaters by bacterial isolates are the focus of this review article in addition to a discussion on toxicity of Cr(VI) on bacterial strains and various factors affecting Cr(VI) bioreduction.

  7. Cytotoxicity and oxidative mechanisms of different forms of chromium.

    PubMed

    Bagchi, Debasis; Stohs, Sidney J; Downs, Bernard W; Bagchi, Manashi; Preuss, Harry G

    2002-10-30

    Chromium exists mostly in two valence states in nature: hexavalent chromium [chromium(VI)] and trivalent chromium [chromium(III)]. Chromium(VI) is commonly used in industrial chrome plating, welding, painting, metal finishes, steel manufacturing, alloy, cast iron and wood treatment, and is a proven toxin, mutagen and carcinogen. The mechanistic cytotoxicity of chromium(VI) is not completely understood, however, a large number of studies demonstrated that chromium(VI) induces oxidative stress, DNA damage, apoptotic cell death and altered gene expression. Conversely, chromium(III) is essential for proper insulin function and is required for normal protein, fat and carbohydrate metabolism, and is acknowledged as a dietary supplement. In this paper, comparative concentration- and time-dependent effects of chromium(VI) and chromium(III) were demonstrated on increased production of reactive oxygen species (ROS) and lipid peroxidation, enhanced excretion of urinary lipid metabolites, DNA fragmentation and apoptotic cell death in both in vitro and in vivo models. Chromium(VI) demonstrated significantly higher toxicity as compared with chromium(III). To evaluate the role of p53 gene, the dose-dependent effects of chromium(VI) were assessed in female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of ROS, lipid peroxidation and DNA fragmentation in hepatic and brain tissues. Chromium(VI) induced more pronounced oxidative damage in multiple target organs in p53 deficient mice. Comparative studies of chromium(III) picolinate and niacin-bound chromium(III), two popular dietary supplements, reveal that chromium(III) picolinate produces significantly more oxidative stress and DNA damage. Studies have implicated the toxicity of chromium picolinate in renal impairment, skin blisters and pustules, anemia, hemolysis, tissue edema, liver dysfunction; neuronal cell injury, impaired cognitive, perceptual and motor activity; enhanced production of hydroxyl

  8. Lateral stress evolution in chromium sulfide cermets with varying excess chromium

    NASA Astrophysics Data System (ADS)

    Petel, O. E.; Appleby-Thomas, G. J.; Wood, D. C.; Capozzi, A.; Nabavi, A.; Goroshin, S.; Frost, D. L.; Hazell, P. J.

    2016-04-01

    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a one-dimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium contents.

  9. Diffusion of chromium in chrysoberyl

    NASA Astrophysics Data System (ADS)

    Ahn, Yong-Kil; Seo, Jin-Gyo; Park, Jong-Wan

    2009-07-01

    Cr 3+ diffusion in chrysoberyl (BeAl 2O 4) irradiated by H + ions and electrons has been studied and compared with diffusion in non-irradiated samples. Chrysoberyl crystals were irradiated with 6 MeV H + ions to fluencies of 1×10 16 cm -2 for 25 min and with 10 MeV electrons to fluencies of 2×10 17 cm -2 for 1 h. Three different types of samples, which were doped with Cr 3+, were annealed in horizontal alumina tube furnaces by 50 K intervals in the temperature range from 1773 to 1923 K for 200 h. Scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX) was used to measure the diffusion. Arrhenius equations for the diffusion coefficient for Cr 3+ in the temperature range 1773-1923 K were developed: Electron beam irradiated chrysoberyls, Dcr=2.1×10 -5×exp (-482.3±18.2 kJ mol -1/ RT)m 2 s -1 Proton beam irradiated chrysoberyls, Dcr=2.3×10 -3×exp (-545.4±25.0 kJ mol -1/ RT)m 2 s -1 Natural non-irradiated chrysoberyls Dcr=2.2×10 -3×exp (-547.9±36.8 kJ mol -1/ RT)m 2 s -1 The results indicate that the chromium diffuses deepest into the electron beam irradiated chrysoberyls.

  10. Oral Chromium Exposure and Toxicity

    PubMed Central

    Sun, Hong; Brocato, Jason

    2015-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen when inhaled. However, inhalational exposure to Cr(VI) affects only a small portion of the population, mainly by occupational exposures. In contrast, oral exposure to Cr(VI) is widespread and affects many people throughout the globe. In 2008, the National Toxicology Program (NTP) released a 2-year study demonstrating that ingested Cr(VI) was carcinogenic in rats and mice. The effects of Cr(VI) oral exposure is mitigated by reduction in the gut, however a portion evades the reductive detoxification and reaches target tissues. Once Cr(VI) enters the cell, it ultimately gets reduced to Cr(III), which mediates its toxicity via induction of oxidative stress during the reduction while Cr intermediates react with protein and DNA. Cr(III) can form adducts with DNA that may lead to mutations. This review will discuss the potential adverse effects of oral exposure to Cr(VI) by presenting up-to-date human and animal studies, examining the underlying mechanisms that mediate Cr(VI) toxicity, as well as highlighting opportunities for future research. PMID:26231506

  11. Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol

    NASA Astrophysics Data System (ADS)

    Aktas, S.; Eyuboglu, C.; Morcali, M. H.; Özbey, S.; Sucuoglu, Y.

    2015-05-01

    In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K2Cr2O7 than Na2Cr2O7. On the other hand, in the strongly acidic regime, ethanol acted as a reducing agent role in that chromium(VI) was converted into Cr(III) whereas ethanol itself was oxidized to carbon dioxide and water. Subsequently, chromium hydroxide was obtained by the help of sodium hydroxide and converted to chromium oxide by heating at 800 °C, as indicated in thermo gravimetric analysis (TGA).

  12. Chromium Recycling in the United States in 1998

    USGS Publications Warehouse

    Papp, John F.

    2001-01-01

    The purpose of this report is to illustrate the extent to which chromium was recycled in the United States in 1998 and to identify chromium-recycling trends. The major use of chromium was in the metallurgical industry to make stainless steel; substantially less chromium was used in the refractory and chemical industries. In this study, the only chromium recycling reported was that which was a part of stainless steel scrap reuse. In 1998, 20 percent of the U.S. apparent consumption of chromium was secondary (from recycling); the remaining 80 percent was based on net chromium commodity imports and stock adjustments. Chromite ore was not mined in the United States in 1998. In 1998, 75,300 metric tons (t) of chromium contained in old scrap was consumed in the United States; it was valued at $66.4 million. Old scrap generated contained 132,000 t of chromium. The old scrap recycling efficiency was 87 percent, and the recycling rate was 20 percent. About 18,000 t of chromium in old scrap was unrecovered. New scrap consumed contained 28,600 t of chromium, which yielded a new-to-old-scrap ratio of 28:72. U.S. chromium-bearing stainless steel scrap net exports were valued at $154 million and were estimated to have contained 41,000 t of chromium.

  13. Reduction of hexavalent chromium collected on PVC filters.

    PubMed

    Shin, Y C; Paik, N W

    2000-01-01

    Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.

  14. The enriched chromium neutrino source for GALLEX

    SciTech Connect

    Hartmann, F.X.; Hahn, R.L.

    1991-01-18

    The preparation and study of an intense source of neutrinos in the form of neutron irradiated materials which are enriched in Cr-50 for use in the GALLEX solar neutrino experiment are discussed. Chromyl fluoride gas is enriched in the Cr-50 isotope by gas centrifugation and subsequently converted to a very stable form of chromium oxide. The results of neutron activation analyses of such chromium samples indicate low levels of any long-lived activities, but show that short-lived activities, in particular Na-24, may be of concern. These results show that irradiating chromium oxide enriched in Cr-50 is preferable to irradiating either natural chromium or argon gas as a means of producing a neutrino source to calibrate the GALLEX detector. These results of the impurity level analysis of the enriched chromyl fluoride gas and its conversion to the oxide are also of interest to work in progress by other members of the Collaboration investigating an alternative conversion of the enriched gas to chromium metal. 35 refs., 12 figs., 5 tabs.

  15. [Occupational exposure to chromium(VI) compounds].

    PubMed

    Skowroń, Jolanta; Konieczko, Katarzyna

    2015-01-01

    This article discusses the effect of chromium(VI) (Cr(VI)) on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI) compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV) for chromium(VI) of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL) document chromium(VI) concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2-14 cases per 1000 exposed workers. Exposure to chromium(VI) compounds expressed in Cr(VI) of 0.01 mg Cr(VI)/m3; is responsible for the increased number of lung cancer cases in 1-6 per 1000 people employed in this condition for the whole period of professional activity.

  16. Phytotoxic lesions of chromium in maize.

    PubMed

    Sharma, D C; Sharma, C P; Tripathi, R D

    2003-04-01

    Chromium (Cr) is fairly abundant in the earth's crust and ranks fourth among the 29 elements of biological importance. Besides natural sources, Cr enters biotic components of the ecosystem in various ways. Of other major industrial sources, tanning and chrome-plating industries are prominent sources. Cr(VI) form of chromium is highly reactive and influences both plants and animals. Due to Mn present in soil, Cr(III) is oxidized to Cr(VI) which remains in soil for a long time and can affect plant growth and development. Since maize is an important food and fodder plant for human beings and cattle, a study was conducted to investigate the effects of Cr on some metabolic activities of maize (Zea mays L. cv. Ganga 5). Chromium caused visible lesions of interveinal chlorosis. Young leaves showed vein clearing. Also, a papery appearance was observed in leaves. Margins of leaves were curled and the leaves appeared pale at greater Cr exposure. Concentrations of both chlorophyll a and b were reduced by exposure to Cr, the activities of ribonuclease and phenyl phosphatase were greater while the activity of iron-porphyrin enzyme catalase was less and the activity of amylase was also much less in plants exposed to Cr. Chromium also caused retardation of soluble protein. Accumulation of Cr in roots was much at all the levels of chromium supply. Exposure to Cr resulted in reduction in grain production and quality.

  17. 76 FR 8773 - Superalloy Degassed Chromium From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... 2010 to determine whether revocation of the antidumping duty order on superalloy degassed chromium...

  18. Natural Attenuation of Hexavalent Chromium in Groundwater and Soils

    EPA Pesticide Factsheets

    Concerns about the impact of chromium on human health and the environment require an evaluation of the potential risk of chromium entering the groundwater flow system and being transported beyond compliance boundaries.

  19. Unusual reactivity in a commercial chromium supplement compared to baseline DNA cleavage with synthetic chromium complexes.

    PubMed

    Chaudhary, Shveta; Pinkston, Joel; Rabile, M Mohamed; Van Horn, J David

    2005-03-01

    Commercially available chromium supplements were tested for their DNA cleavage ability compared with synthetic chromium(III) complexes, including chromium(III) tris-picolinate [Cr(pic)3], basic chromium acetate [Cr3O(OAc)6]+, model complexes, and recently patented Cr-complexes for use in supplements or therapy. Four different supplements (P1-P4) were tested for their DNA cleaving activity in the presence and the absence of H2O2, dithiothreitol (DTT) or ascorbate. One supplement, P1, showed nicking of DNA in the absence of oxidant or reductant at 120 microM metal concentration. Different lot numbers of P1 were also tested for DNA cleavage activity with similar results. Commercial supplements containing Cr(pic)3 nicked DNA at 120 microM metal concentrations in the presence of 5 mM ascorbate or with excess hydrogen peroxide, analogous to reactions with synthetic Cr(pic)3 reported elsewhere. Another chromium (non-Cr(pic)3) supplement, P2, behaves in a comparable manner to simple Cr(III) salts in the DNA nicking assay. Chromium(III) malonate [Cr(mal)2] and chromium(III) acetate [Cr(OAc)] can nick DNA in the presence of ascorbate or hydrogen peroxide, respectively, only at higher metal concentrations. The Cr(III) complexes of histidine, succinate or N-acetyl-L-glutamate do not nick DNA to a significant degree.

  20. In vivo effects of chromium.

    PubMed Central

    Witmer, C; Faria, E; Park, H S; Sadrieh, N; Yurkow, E; O'Connell, S; Sirak, A; Schleyer, H

    1994-01-01

    The production of reactive oxygen species on addition of hexavalent chromium (potassium dichromate, K2Cr2O7) to lung cells in culture was studied using flow cytometer analysis. A Coulter Epics Profile II flow cytometer was used to detect the formation of reactive oxygen species after K2Cr2O7 was added to A549 cells grown to confluence. The cells were loaded with the dye, 2',7'-dichlorofluorescein diacetate, after which cellular esterases removed the acetate groups and the dye was trapped intracellularly. Reactive oxygen species oxidized the dye, with resultant fluorescence. Increased doses of Cr(VI) caused increasing fluorescence (10-fold higher than background at 200 microM). Addition of Cr(III) compounds, as the picolinate or chloride, caused no increased fluorescence. Electron paramagnetic resonance (EPR) spectroscopic studies indicated that three (as yet unidentified) spectral "signals" of the free radical type were formed on addition of 20, 50, 100, and 200 microM Cr(VI) to the A549 cells in suspension. Two other EPR "signals" with the characteristics of Cr(V) entities were seen at field values lower than the standard free radical value. Liver microsomes from male Sprague-Dawley rats treated intraperitoneally with K2Cr2O7 (130 mumole/kg every 48 hr for six treatments) had decreased activity of cytochromes P4503A1 and/or 3A2, and 2C11. Hepatic microsomes from treated female Sprague-Dawley rats, in contrast, had increased activities of these isozymes. Lung microsomes from male Sprague-Dawley rats had increased activity of P4502C11. Images Figure 4. Figure 6. PMID:7843092

  1. Chromium picolinate supplementation for diabetes mellitus.

    PubMed

    Fox, G N; Sabovic, Z

    1998-01-01

    Chromium picolinate is a widely available nutritional supplement marketed for a plethora of afflictions. There is some evidence, including results from human studies, that it has a role in glucose homeostasis. We report the case of a 28-year-old woman with an 18-year history of type 1 diabetes mellitus whose glycosylated hemoglobin (Hb A1c) declined from 11.3% to 7.9% 3 months after initiation of chromium picolinate, 200 micrograms 3 times daily. Chromium picolinate continues to fall squarely within the scope of "alternative medicine," with both unproven benefits and unknown risks. It deserves closer scrutiny with additional prospective, randomized, double-blind, placebo-controlled trials to evaluate its efficacy in improving outcomes in patients with diabetes. A brief review of the literature was done to assist physicians who are being called upon to counsel and treat patients who are engaging in alternative therapies.

  2. [Occupational asthma caused by chromium and nickel].

    PubMed

    Cruz, María Jesus; Costa, Roser; Marquilles, Eduard; Morell, Ferran; Muñoz, Xavier

    2006-06-01

    We report the case of a 40-year-old woman who developed occupational asthma following exposure to chromium and nickel in the nickel-plating section of a metalworks company. Skin prick tests for specific antibodies proved positive for nickel chloride at a concentration of 1 mg/mL and negative for potassium dichromate. The specific bronchial provocation test confirmed the diagnosis of occupational asthma due to exposure to chromium and nickel. The patient presented a late positive reaction to nickel chloride (0.1 mg/mL) and an immediate positive reaction to a 10 mg/mL solution of potassium dichromate. These results indicate a dual response to nickel and chromium in this patient.

  3. 21 CFR 73.2326 - Chromium hydroxide green.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  4. 21 CFR 73.1327 - Chromium oxide greens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color...

  5. 21 CFR 73.1326 - Chromium hydroxide green.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  6. 21 CFR 73.2326 - Chromium hydroxide green.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  7. 21 CFR 73.2327 - Chromium oxide greens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to...

  8. 48 CFR 252.223-7008 - Prohibition of Hexavalent Chromium.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Chromium. 252.223-7008 Section 252.223-7008 Federal Acquisition Regulations System DEFENSE ACQUISITION... of Provisions And Clauses 252.223-7008 Prohibition of Hexavalent Chromium. As prescribed in 223.7306, use the following clause: Prohibition of Hexavalent Chromium (JUN 2013) (a) Definitions. As used...

  9. 21 CFR 73.2327 - Chromium oxide greens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to...

  10. 21 CFR 73.1326 - Chromium hydroxide green.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  11. 21 CFR 73.2327 - Chromium oxide greens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to...

  12. Hexavalent and trivalent chromium in leather: What should be done?

    PubMed

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions.

  13. 21 CFR 73.2326 - Chromium hydroxide green.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  14. 21 CFR 73.2326 - Chromium hydroxide green.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  15. 21 CFR 73.2327 - Chromium oxide greens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to...

  16. 21 CFR 73.3111 - Chromium oxide greens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium oxide greens. 73.3111 Section 73.3111... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3111 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens (chromic oxide) (CAS Reg. No....

  17. 21 CFR 73.1327 - Chromium oxide greens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color...

  18. 21 CFR 73.1326 - Chromium hydroxide green.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  19. 21 CFR 73.2326 - Chromium hydroxide green.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  20. 48 CFR 252.223-7008 - Prohibition of Hexavalent Chromium.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Chromium. 252.223-7008 Section 252.223-7008 Federal Acquisition Regulations System DEFENSE ACQUISITION... of Provisions And Clauses 252.223-7008 Prohibition of Hexavalent Chromium. As prescribed in 223.7306, use the following clause: Prohibition of Hexavalent Chromium (MAY 2011) (a) Definitions. As used...

  1. 21 CFR 73.1326 - Chromium hydroxide green.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  2. 21 CFR 73.1327 - Chromium oxide greens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color...

  3. 21 CFR 73.1327 - Chromium oxide greens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color...

  4. 21 CFR 73.1326 - Chromium hydroxide green.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  5. 48 CFR 252.223-7008 - Prohibition of Hexavalent Chromium.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Chromium. 252.223-7008 Section 252.223-7008 Federal Acquisition Regulations System DEFENSE ACQUISITION... of Provisions And Clauses 252.223-7008 Prohibition of Hexavalent Chromium. As prescribed in 223.7306, use the following clause: Prohibition of Hexavalent Chromium (MAY 2011) (a) Definitions. As used...

  6. 21 CFR 73.2327 - Chromium oxide greens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium oxide greens. 73.2327 Section 73.2327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2327 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens shall conform in identify and specifications to...

  7. 21 CFR 73.3111 - Chromium oxide greens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium oxide greens. 73.3111 Section 73.3111... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3111 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens (chromic oxide) (CAS Reg. No....

  8. 21 CFR 73.1327 - Chromium oxide greens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.1327 Section 73.1327... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1327 Chromium oxide greens. (a) Identity. (1) The color additive chromium oxide greens is principally chromic sesquioxide (Cr2O3). (2) Color...

  9. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-01

    ... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... chromium from Japan. SUMMARY: The Commission hereby gives notice that it has instituted a review pursuant... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to...

  10. 21 CFR 73.3111 - Chromium oxide greens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium oxide greens. 73.3111 Section 73.3111... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3111 Chromium oxide greens. (a) Identity and specifications. The color additive chromium oxide greens (chromic oxide) (CAS Reg. No....

  11. Protective claddings for high strength chromium alloys

    NASA Technical Reports Server (NTRS)

    Collins, J. F.

    1971-01-01

    The application of a Cr-Y-Hf-Th alloy as a protective cladding for a high strength chromium alloy was investigated for its effectiveness in inhibiting nitrogen embrittlement of a core alloy. Cladding was accomplished by a combination of hot gas pressure bonding and roll cladding techniques. Based on bend DBTT, the cladding alloy was effective in inhibiting nitrogen embrittlement of the chromium core alloy for up to 720 ks (200hours) in air at 1422 K (2100 F). A significant increase in the bend DBTT occurred with longer time exposures at 1422 K or short time exposures at 1589 K (2400 F).

  12. Chromium isotopic anomalies in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.

    1986-01-01

    Abundances of the chromium isotopes in terrestrial and bulk meteorite samples are identical to 0.01 percent. However, Ca-Al-rich inclusions from the Allende meteorite show endemic isotopic anomalies in chromium which require at least three nucleosynthetic components. Large anomalies at Cr-54 in a special class of inclusions are correlated with large anomalies at Ca-48 and Ti-50 and provide strong support for a component reflecting neutron-rich nucleosynthesis at nuclear statistical equilibrium. This correlation suggests that materials from very near the core of an exploding massive star may be injected into the interstellar medium.

  13. Strategies for chromium bioremediation of tannery effluent.

    PubMed

    Garg, Satyendra Kumar; Tripathi, Manikant; Srinath, Thiruneelakantan

    2012-01-01

    Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and

  14. The Neel temperatures of nanocrystalline chromium

    SciTech Connect

    Fitzsimmons, M.R.; Robinson, R.A.; Eastman, J.A.; Lynn, J.W.

    1994-07-01

    Wide-angle neutron diffraction measurements at temperatures from 6 to 250 K indicate that the major portion of a nanocrystalline chromium sample with a mean grain size of 73 nm becomes antiferromagnetically ordered at 119 {plus_minus} 10 K. The remainder of the sample has a Neel temperature above 250 K, as expected for coarse-grained chromium. No evidence for antiferromagnetic order in a second sample with a mean grain size of 11 nm was observed, even to temperatures as low as 6 K.

  15. The Preparation of Chromium by the Thermal Decomposition of Chromium Iodide

    DTIC Science & Technology

    2014-05-15

    chromium with iodine vapor, the sublimation of the chromium iodide, and its subsequent decomposition on a hot tungsten filament, all in an evacuated...heated with a gas burner while iodine from the bulb was vaporized and passed over it. As the iodine vapor passed over the hot metal, a condensate was v...of iodine was exhausted, the apparatus was broken ~pen and the contents examined. The reaction product was very hygro- scopic, forming a green

  16. Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects.

    PubMed

    Lindström, David; Hedberg, Yolanda; Odnevall Wallinder, Inger

    2010-06-01

    The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site.

  17. Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

    PubMed

    Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

    2016-06-01

    The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively.

  18. Dermatitis from a chromium dental plate.

    PubMed

    Hubler, W R; Hubler, W R

    1983-09-01

    Systemic absorption of metal or metallic salts from dental and orthopedic surgical implants can produce a cutaneous allergic dermatitis in susceptible individuals. Mercury, nickel and cobalt are the most common metals to elicit such systemic allergic reactions from chronic internal exposure. A case is presented of a generalized eczematoid dermatitis apparently caused by allergy to chromium liberated from a metal dental plate.

  19. Method for welding chromium molybdenum steels

    DOEpatents

    Sikka, Vinod K.

    1986-01-01

    Chromium-molybdenum steels exhibit a weakening after welding in an area adjacent to the weld. This invention is an improved method for welding to eliminate the weakness by subjecting normalized steel to a partial temper prior to welding and subsequently fully tempering the welded article for optimum strength and ductility.

  20. Nickel-chromium-silicon brazing filler metal

    DOEpatents

    Martini, Angelo J.; Gourley, Bruce R.

    1976-01-01

    A brazing filler metal containing, by weight percent, 23-35% chromium, 9-12% silicon, a maximum of 0.15% carbon, and the remainder nickel. The maximum amount of elements other than those noted above is 1.00%.

  1. 29 CFR 1910.1026 - Chromium (VI).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... anticipated future exposure to chromium (VI); any history of respiratory system dysfunction; any history of... them by the use of respiratory protection that complies with the requirements of paragraph (g) of this... respiratory protection that complies with the requirements of paragraph (g) of this section to achieve the...

  2. 29 CFR 1926.1126 - Chromium (VI).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... use of respiratory protection that complies with the requirements of paragraph (f) of this section... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  3. 29 CFR 1926.1126 - Chromium (VI).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... use of respiratory protection that complies with the requirements of paragraph (f) of this section... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  4. 29 CFR 1915.1026 - Chromium (VI).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... them by the use of respiratory protection that complies with the requirements of paragraph (f) of this... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  5. 29 CFR 1915.1026 - Chromium (VI).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... them by the use of respiratory protection that complies with the requirements of paragraph (f) of this... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  6. 29 CFR 1910.1026 - Chromium (VI).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... anticipated future exposure to chromium (VI); any history of respiratory system dysfunction; any history of... them by the use of respiratory protection that complies with the requirements of paragraph (g) of this... respiratory protection that complies with the requirements of paragraph (g) of this section to achieve the...

  7. 29 CFR 1910.1026 - Chromium (VI).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... anticipated future exposure to chromium (VI); any history of respiratory system dysfunction; any history of... them by the use of respiratory protection that complies with the requirements of paragraph (g) of this... respiratory protection that complies with the requirements of paragraph (g) of this section to achieve the...

  8. 29 CFR 1926.1126 - Chromium (VI).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... use of respiratory protection that complies with the requirements of paragraph (f) of this section... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  9. 29 CFR 1915.1026 - Chromium (VI).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chromium (VI); any history of respiratory system dysfunction; any history of asthma, dermatitis, skin... them by the use of respiratory protection that complies with the requirements of paragraph (f) of this... achieve compliance with the PEL. (f) Respiratory protection—(1) General. Where respiratory protection...

  10. 29 CFR 1910.1026 - Chromium (VI).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... anticipated future exposure to chromium (VI); any history of respiratory system dysfunction; any history of... them by the use of respiratory protection that complies with the requirements of paragraph (g) of this... respiratory protection that complies with the requirements of paragraph (g) of this section to achieve the...

  11. 29 CFR 1910.1026 - Chromium (VI).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... anticipated future exposure to chromium (VI); any history of respiratory system dysfunction; any history of... them by the use of respiratory protection that complies with the requirements of paragraph (g) of this... respiratory protection that complies with the requirements of paragraph (g) of this section to achieve the...

  12. Effects of chromium on the immune system.

    PubMed

    Shrivastava, Richa; Upreti, R K; Seth, P K; Chaturvedi, U C

    2002-09-06

    Chromium is a naturally occurring heavy metal found commonly in the environment in trivalent, Cr(III), and hexavalent, Cr(VI), forms. Cr(VI) compounds have been declared as a potent occupational carcinogen among workers in chrome plating, stainless steel, and pigment industries. The reduction of Cr(VI) to Cr(III) results in the formation of reactive intermediates that together with oxidative stress oxidative tissue damage and a cascade of cellular events including modulation of apoptosis regulatory gene p53, contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. On the other hand, chromium is an essential nutrient required to promote the action of insulin in body tissues so that the body can use sugars, proteins and fats. Chromium is of significant importance in altering the immune response by immunostimulatory or immunosuppressive processes as shown by its effects on T and B lymphocytes, macrophages, cytokine production and the immune response that may induce hypersensitivity reactions. This review gives an overview of the effects of chromium on the immune system of the body.

  13. Hygienic behaviour in chromium plating industries.

    PubMed

    Lumens, M E; Ulenbelt, P; Géron, H M; Herber, R F

    1993-01-01

    The impact of hygienic behaviour on the uptake of chromium has been studied in two small chromium plating factories. The correlation between the environmental monitoring measure (Cr-A) and the biological monitoring measure (Cr-U) varied between the two factories. In one factory (I) the correlation between Cr-U and Cr-A was 0.68 (P < 0.001), while in the other factory (II) it was negative (r = -0.64, P = 0.03). However, in both populations a significant impact of hygienic behaviour on the variance in Cr-U levels could be detected. In factory I, explained variance could be enhanced to R2 = 0.94 (P < 0.001) when considering expressions of hygienic behaviour. In factory II, a strong relation proved to exist between Cr-U and dermal uptake. For the various questions referring to skin problems and possible dermal uptake, the correlation with Cr-U is up to 0.70 (P = 0.03). When comparing the results for the two factories, it is shown that in addition to individual differences in hygienic behaviour, general hygienic conditions also have an impact on uptake of chromium. In factory II, where many efforts were made to prevent exposure to chromium, Cr-U was significantly lower than in factory I (P < 0.001).

  14. Trivalent Chromium Conversion Coatings for Aluminum

    DTIC Science & Technology

    1993-09-27

    salts corrosion. This is without any hexavalent chromium in the bath. The absence of Cr+ 6 was determined by analysis of the bath by atomic absorption spectroscopy and...coating was determined by dissolving the films 5 minutes in 25% (vol.) HC1 at 250 C and analyzing for Cr 20 by atomic absorption spectroscopy . The solution

  15. Chemical behavior of acidified chromium (3) solutions

    SciTech Connect

    Terman, D.K.

    1981-05-01

    A unique energy-storage system has been developed at NASA's Lewis Research Center called REDOX. This NASA-REDOX system is an electrochemical storage device that utilized the oxidation and reduction of two fully soluble redox couples for charging and discharging. The redox couples now being investigated are acidified chloride solutions of chromium (Cr(+2)/Cr(+3)) and iron (Fe(+2)/Fe(+3)).

  16. Synthesis and Characterization of New Copper-Chromium Layered Double Hydroxides Pillared with Polyoxovanadates

    NASA Astrophysics Data System (ADS)

    Depège, C.; Bigey, L.; Forano, C.; de Roy, A.; Besse, J. P.

    1996-11-01

    In this study, we have focused on the intercalation by ion-exchange of some polyoxovanadate anions from aqueous solution (decavanadate V10O6-28, tetravanadate V4O4-12, and pyrovanadate V2O4-7) into the layers of a copper chromium hydrotalcite-like compound. PXRD, FTIR, TGA, and EXAFS studies have provided information about the specific oxovanadate ions in the interlayers and their orientation. Thermal treatment of these LDHs was also examined. A grafting process of pyrovanadate anions onto the hydroxylated sheets has been demonstrated at room temperature.

  17. 40 CFR 503.47 - Recordkeeping.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... retain that information for five years. (b) The concentration of lead, arsenic, cadmium, chromium, and..., arsenic, cadmium, chromium, and nickel for each sewage sludge incinerator. (m) The risk...

  18. Hexavalent chromium removal from aqueous solutions by a novel powder prepared from Colocasia esculenta leaves.

    PubMed

    Nakkeeran, E; Saranya, N; Giri Nandagopal, M S; Santhiagu, A; Selvaraju, N

    2016-08-02

    In this study, batch removal of hexavalent chromium from aqueous solutions by powdered Colocasia esculenta leaves was investigated. Batch experiments were conducted to study the effects of adsorption of Cr(VI) at different pH values, initial concentrations, agitation speeds, temperatures, and contact times. The biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrometer analysis. The biosorptive capacity of the adsorbent was dependent on the pH of the chromium solution in which maximum removal was observed at pH 2. The adsorption equilibrium data were evaluated for various adsorption isotherm models, kinetic models, and thermodynamics. The equilibrium data fitted well with Freundlich and Halsey models. The adsorption capacity calculated was 47.62 mg/g at pH 2. The adsorption kinetic data were best described by pseudo-second-order kinetic model. Thus, Colocasia esculenta leaves can be considered as one of the efficient and cheap biosorbents for hexavalent chromium removal from aqueous solutions.

  19. Estimation of Release of Nickel and Chromium by Indian Made Orthodontic Appliance in Saliva

    PubMed Central

    Parashar, Sandeep; Gupta, Ankur; Hegde, Chatura; Anand, Neelima

    2015-01-01

    Introduction With increasing use of Indian made orthodontic materials, need was felt to know nickel and chromium release from these material. Materials and Methods This study was conducted on simulated appliances consisting of brackets (022″Roth, Modern orthodontics, Ludhiana, India), from second premolar to central incisor, buccal tube and 0.019×0.025- inch SS arch wires secured with SS ligatures. Immersion was done in artificial saliva. Samples were analysed to using Atomic Absorption Photospectrometer (GVC ScientificEquipment Pvt. Ltd Australia) at AES Laboratories (P) Ltd., Noida India on 1st, 7th, 14th and 28th day. Results SPSS (ver 17, Inc., Chicago, Illinois, USA) was used toperform the statistical analysis. Descriptive statistics i.e. median and 25 and75 percentiles were used. Peak nickel release was on 7th day and subsequently declined over 14th and 28th day. The peak level of chromium concentration was on 14th day, which declined thereafter. Conclusion Average daily release of nickel and chromium over a period of one month was 97.368 μg/day and 47.664 μg/day respectively. The estimated release rates were approximately 32% and 16% of the reported average daily dietary. PMID:26501018

  20. Chromium(II) and chromium(II) tri-tert-butoxysiloxy complexes

    SciTech Connect

    Terry, K.W.; Gantzel, P.K.; Tilley, T.D. )

    1993-11-10

    The authors have been exploring the structure, bonding, and chemistry of transition-metal and main-group complexes that possess oxygen-rich alkoxysiloxy ligands such as [minus]OSi(O[sup t]Bu)[sub 3]. A primary focus of these studies is the development of molecular, single-source precursors to homogeneous, ultrapure metal silicates. The authors have found that titanium, zirconium, hafnium, and aluminum derivatives of [minus]OSi(O[sup t]Bu)[sub 3] thermally decompose at low temperatures (100-200[degrees]C) with elimination of isobutylene and water to give metal-containing silicates. Previous observations suggested the possible use of this methodology in new syntheses of supported catalysts, particularly since chemical reactivities and selectivities are known to be very sensitive to the size and shape of the supported metal catalyst particles. Silica- and aluminosilica-supported chromium catalysts are used widely for the catalytic polymerization of ethylene. To examine alkoxysiloxy derivatives of chromium as precursors to chromium-supported catalysts, the authors have begun to explore synthetic routes to Cr-OSi(O[sup t]Bu)[sub 3] complexes. On the basis of previously reported routes to siloxide and alkoxide complexes of chromium, approaches based on either the silanol HOSi(O[sup t]Bu)[sub 3] or alkali metal derivatives MOSi(O[sup t]Bu)[sub 3] (M = Li, Na, K) as starting materials seem possible. The authors report two siloxide complexes which result from the reaction of Cr(NEt[sub 2])[sub 4] with HOSi(O[sup t]Bu)[sub 3]. While this reaction does not provide a high yield of a single product that can be used in a convenient route to chromium silicate materials, it does offer the opportunity to closely compare analogous chromium(II) and chromium(III) siloxide complexes Cr[OSi(O[sup t]Bu)[sub 3

  1. Chromium supplementation improved post-stroke brain infarction and hyperglycemia.

    PubMed

    Chen, Wen-Ying; Mao, Frank Chiahung; Liu, Chia-Hsin; Kuan, Yu-Hsiang; Lai, Nai-Wei; Wu, Chih-Cheng; Chen, Chun-Jung

    2016-04-01

    Hyperglycemia is common after acute stroke and is associated with a worse outcome of stroke. Thus, a better understanding of stress hyperglycemia is helpful to the prevention and therapeutic treatment of stroke. Chromium is an essential nutrient required for optimal insulin activity and normal carbohydrate and lipid metabolism. Beyond its nutritional effects, dietary supplement of chromium causes beneficial outcomes against several diseases, in particular diabetes-associated complications. In this study, we investigated whether post-stroke hyperglycemia involved chromium dynamic mobilization in a rat model of permanent focal cerebral ischemia and whether dietary supplement of chromium improved post-stroke injury and alterations. Stroke rats developed brain infarction, hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Post-stroke hyperglycemia was accompanied by elevated secretion of counter-regulatory hormones including glucagon, corticosterone, and norepinephrine, decreased insulin signaling in skeletal muscles, and increased hepatic gluconeogenesis. Correlation studies revealed that counter-regulatory hormone secretion showed a positive correlation with chromium loss and blood glucose increased together with chromium loss. Daily chromium supplementation increased tissue chromium levels, attenuated brain infarction, improved hyperglycemia, and decreased plasma levels of glucagon and corticosterone in stroke rats. Our findings suggest that stroke rats show disturbance of tissue chromium homeostasis with a net loss through urinary excretion and chromium mobilization and loss might be an alternative mechanism responsible for post-stroke hyperglycemia.

  2. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    PubMed

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept.

  3. Distribution and significance of chromium in meteorites

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Olsen, E.

    1975-01-01

    Chromium is present as a minor element in all meteorite types. Depending on the meteorite type it is lithophile (most frequent), chalcophile (less frequent), or siderophile (rare). Chromium is an indicator of physical and chemical conditions of meteorite formation, especially of the state of oxidation. The Cr contents of meteoritic chromites are related to classification and can be used to distinguish among meteorite types that contain this mineral. The distribution of Cr between coexisting pyroxenes may indicate the degree of equilibration of this mineral pair. Siderophile Cr appears to result from primitive condensation processes rather than secondary reduction processes. The lack of much experimental data on Cr in silicate systems limits the interpretation of the occurrences of Cr-silicate phases, ureyite and krinovite, in the meteorite type in which they occur.

  4. New mixed aluminium–chromium diarsenate

    PubMed Central

    Bouhassine, Mohamad Alem; Boughzala, Habib

    2017-01-01

    Potassium chromium aluminium diarsenate, KCr1/4Al3/4As2O7, was prepared by solid-state reaction. The structure consists of (Cr1/4/Al3/4)O6 octa­hedra and As2O7 diarsenate groups sharing corners to build up a three-dimensional anionic framework. The potassium cations are located in wide channels running along the c-axis direction. The crystal structure is isostructural with the triclinic A I M III X 2O7 (A I = alkali metal; M III = Al, Cr, Fe; X = As, P) compounds. However, the M III octa­hedrally coordinated site is 25% partially occupied by chromium and 75% by aluminium. PMID:28316805

  5. X-616 Chromium Sludge Lagoons pictorial overview, Piketon, Ohio

    SciTech Connect

    Not Available

    1992-10-01

    The Portsmouth Gaseous Diffusion Plant uses large quantities of water for process cooling. The X-616 Liquid Effluent Control Facility was placed in operation in December 1976 to treat recirculation cooling water blowdown from the process cooling system. A chromium-based corrosion inhibitor was used in the cooling water system. A chromium sludge was produced in a clarifier to control chromium levels in the water. Chromium sludge produced by this process was stored in two surface impoundments called the X-616 Chromium Sludge Lagoons. The sludge was toxic due to its chromium concentration and therefore required treatment. The sludge was treated, turning it into a sanitary waste, and buried in an Ohio EPA approved landfill. The plant's process cooling water system has changed to a more environmentally acceptable phosphate-based inhibitor. Closure activities at X-616 began in August 1990, with all construction activities completed in June 1991, at a total cost of $8.0 million.

  6. Speciation and recovery of chromium from chromite ore processing residues.

    PubMed

    Sreeram, K J; Ramasami, T

    2001-10-01

    The processing of chromite ore is associated with the generation of large quantities of solid wastes containing chromium, which have been disposed of as landfill for many years. The mobilization and operational speciation of chromium contained in soils contaminated with metal salts are important in terms of the environment. Several methods have been employed for the extraction and recovery of solid wastes. Chromium contained in contaminated soils and solid wastes can be categorized as exchangeable, oxidizable, carbonate-bound, reducible and residual. The results from this study indicate a need for efficient leaching methodologies in chromite ore processing plants to decrease the non-detrital fractions of chromium in the residue. Aggressive methodologies are required to recover chromium from the detrital fractions. The potential benefits of employing sodium peroxide for the complete recovery of chromium from chromite residue have been demonstrated, and the need to ensure the safety of the process has been emphasized.

  7. Laser action in chromium-doped forsterite

    NASA Technical Reports Server (NTRS)

    Petricevic, V.; Gayen, S. K.; Alfano, R. R.; Yamagishi, Kiyoshi; Anzai, H.

    1988-01-01

    This paper reports on pulsed laser operation obtained in chromium-activated forsterite Cr(3+):Mg2SiO4 at room temperature. The spectrum of the free-running laser peaks at 1235 nm and a bandwidth of about 22 nm. The spectral range of the laser emission is expected to extend from 850 to 1300, provided the parasitic impurity absorption may be minimized by improved crystal growth techique.

  8. Observational Approach to Chromium Site Remediation - 13266

    SciTech Connect

    Scott Myers, R.

    2013-07-01

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the observational

  9. Method for welding chromium molybdenum steels

    SciTech Connect

    Sikka, V.K.

    1986-09-16

    A process is described for welding chromium-molybdenum steels which consist of: subjecting the steel to normalization by heating to above the transformation temperature and cooling in air; subjecting the steel to a partial temper by heating to a temperature less than a full temper; welding the steel using an appropriate filler metal; subjecting the steel to a full temper by heating to a temperature sufficient to optimize strength, reduce stress, increase ductility and reduce hardness.

  10. Dimensionally Controlled Lithiation of Chromium Oxide

    SciTech Connect

    Fister, Tim T.; Hu, Xianyi; Esbenshade, Jennifer; Chen, Xiao; Wu, Jinsong; Dravid, Vinayak; Bedzyk, Michael; Long, Brandon; Gewirth, Andrew A.; Shi, Bing; Schlepütz, Christian M.; Fenter, Paul

    2016-01-12

    Oxide conversion reactions are an alternative approach for high capacity lithium ion batteries but are known to suffer from structural irreversibility associated with the phase separation and reconstitution of reduced metal species and Li2O. In particular, the morphology of the reduced metal species is thought to play a critical role in the electrochemical properties of a conversion material. Here we use a model electrode with alternating layers of chromium and chromium oxide to better understand and control these phase changes in real-time and at molecular length scales. Despite lacking crystallinity at the atomic scale, this superstructure is observed (with X-ray reflectivity, XR) to lithiate and delithiate in a purely one-dimensional manner, preserving the layered structure. The XR data show that the metal layers act as nucleation sites for the reduction of chromium in the conversion reaction. Irreversibility during delithiation is due to the formation of a ternary phase, LiCrO2, which can be further delithiated at higher potentials. The results reveal that the combination of confining lithiation to nanoscale sheets of Li2O and the availability of reaction sites in the metal layers in the layered structure is a strategy for improving the reversibility and mass transport properties that can be used in a wide range of conversion materials.

  11. Chromium oxidation state mapping in human cells

    NASA Astrophysics Data System (ADS)

    Ortega, R.; Fayard, B.; Salomé, M.; Devès, G.; Susini, J.

    2003-03-01

    The widespread use of chromium in industrial applications such as chemical production of pigments, refractory brick production, tanning, metallurgy, electroplating, and combustion of fuels has lead to human occupational exposure and to its increased introduction into the environment. Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation is not known. Up to now, no microanalytical technique was sensitive enough to allow the observation of chromium distribution, and oxidation state identification, within isolated cells at carcinogenic concentrations. In this experiment, we used successfully the ID-21 X-ray microscope to map Cr(VI) and total Cr distributions in cells exposed in vitro to soluble, and insoluble, Cr(VI) compounds. Exposure to soluble compounds, weak carcinogens, resulted in a homogeneous intracellular distribution of Cr, confirming by in situ measurement that Cr is present in the cell nucleus. Cr(VI) was never detected in cells which suggests a mechanism of rapid intracellular reducticn. On the other hand, exposure to insoluble compounds, strong carcinogens, also resulted in a homogeneous distribution of reduced forms of Cr in cells, and their nucleus. However, in this case, Cr(VI)-rich structures were observed into the cells suggesting that carcinogenicity is enhanced when oxidation reactions due to Cr(VI) chronic exposure are associated to Cr-DNA alterations.

  12. Chromium coatings to reduce radiation buildup. Final report

    SciTech Connect

    Galbraith, G.T.; Asay, R.H.; Asay, D.J.

    1995-12-01

    For the past several years, the Electric Power Research Institute (EPRI) has been intensively investigating new methods to mitigate radiation buildup on out-of-core surfaces in light water reactors to reduce occupational radiation exposure. As a result of this work, a new surface preconditioning method termed stabilized chromium has been developed for pretreatment of reactor piping and other components. This treatment method has been shown to be highly effective in retarding radiation buildup. Initial coupon tests of stabilized chromium treatment, an EPRI patented process, showed very favorable results. EPRI is now sponsoring additional development and testing of this preconditioning technique. The specific goals of this project were to investigate the effects of various chromium plating bath compositions, define acceptable chromium plating parameters, and demonstrate the benefit of stabilized chromium treatment by preconditioning actual plant components. Presently, two steam generator manway diaphragms installed at Millstone-2 have been treated with stabilized chromium and are being exposed to primary coolant. After exposure for one fuel cycle the stabilized chromium surfaces had approximately ten times less activity buildup than electropolished-only reference surfaces. Two pipes in the residual heat removal system of Diablo Canyon Unit 2 have also been treated with stabilized and non-stabilized chromium. Initial gamma spectroscopy measurements of these pipes showed the pipe treated with stabilized chromium had the lowest activity buildup. Additional tests of stabilized and non-stabilized chromium films applied to coupon specimens were also conducted at the Doel-2 reactor to evaluate the effect of chromium film thickness on activity buildup. These tests showed thin stabilized chromium films (ca. 3,000 {angstrom}) to be highly effective in retarding activity buildup with reduction factors ranging from 100--150 in comparison to electropolished-only coupons.

  13. Contingency plans for chromium utilization. Publication NMAB-335

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. The effectiveness of programs such as stockpiling, conservation, and research and development for substitutes to reduce the impact of disruption of imports of chromite and ferrochromium are discussed. Alternatives for decreasing chromium consumption also are identified for chromium-containing materials in the areas of design, processing, and substitution.

  14. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Nickel or Chromium-Bearing Materials... FACILITIES Pt. 266, App. XII Appendix XII to Part 266—Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery Furnaces A. Exempt Nickel or Chromium-Bearing Materials...

  15. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery Furnaces XII Appendix XII to Part 266... Processed in Exempt Nickel-Chromium Recovery Furnaces A. Exempt Nickel or Chromium-Bearing Materials...

  16. Safety assessment of chromium by exposure from cosmetic products.

    PubMed

    Hwang, Myungsil; Yoon, Eun Kyung; Kim, Ja Young; Son, Bo Kyung; Yang, Seong Jun; Yun, Mi Ok; Choi, Sang Sook; Jang, Dong Deuk; Yoo, Tae Moo

    2009-02-01

    Low level impurities often reside in cosmetic products. The aim of the present study was to estimate the human exposure to chromium from cosmetic products purchased at a local market in South Korea, and to assess the risk on public health. Hexavalent chromium is an impurity substance that contaminates cosmetic products during manufacture. The potential for chromium to induce and elicit allergic contact dermatitis, as well as the degree of chromium exposure from cosmetic products, were assessed. Chromium exposure was estimated using the chromium concentrations found in cosmetic samples taken from the local market along with the expected user pattern data that was taken from the literature. Of the cosmetics we tested and available for purchase on the Korean market, seven had chromium contents above the detection limit of 0.1 ppm (0.1 microg/mL), ranging from 0.2 to 3.15 ppm. In risk assessment, scientifically defensible dose-response relationships must be established for the end points of concern. In the case of chromium contaminated cosmetic products, this includes conducting dose-response assessments for allergic contact dermatitis following dermal exposure. This dose-response information can then be integrated with site-specific exposure assessments to regulate consumer safety by use of these products. We found that dermal exposure to chromium concentrations ranging from 0.0002 to 0.003 microg/cm(2) does not appear to cause concern for eliciting allergic contact dermatitis.

  17. Method of trivalent chromium concentration determination by atomic spectrometry

    DOEpatents

    Reheulishvili, Aleksandre N.; Tsibakhashvili, Neli Ya.

    2006-12-12

    A method is disclosed for determining the concentration of trivalent chromium Cr(III) in a sample. The addition of perchloric acid has been found to increase the atomic chromium spectrometric signal due to Cr(III), while leaving the signal due to hexavalent chromium Cr(VI) unchanged. This enables determination of the Cr(III) concentration without pre-concentration or pre-separation from chromium of other valences. The Cr(III) concentration may be measured using atomic absorption spectrometry, atomic emission spectrometry or atomic fluorescence spectrometry.

  18. Stabilization and solidification of chromium-contaminated soil

    SciTech Connect

    Cherne, C.A.; Thomson, B.M.; Conway, R.

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  19. Chromium recycling of tannery waste through microbial fermentation.

    PubMed

    Katsifas, E A; Giannoutsou, E; Lambraki, M; Barla, M; Karagouni, A D

    2004-02-01

    An Aspergillus carbonarius isolate, selected from an established microbial culture collection, was used to study the biodegradation of chromium shavings in solid-state fermentation experiments. Approximately 97% liquefaction of the tannery waste was achieved and the liquid obtained from long-term experiments was used to recover chromium. The resulting alkaline chromium sulfate solution was useful in tanning procedures. A proteinaceous liquid was also obtained which has potential applications as a fertilizer or animal feed additive and has several other industrial uses. The A. carbonarius strain proved to be a very useful tool in tannery waste-treatment processes and chromium recovery in the tanning industries.

  20. Studies on the essentiality of chromium in ruminants

    SciTech Connect

    Samsell, L.J.; Spears, J.W.

    1986-03-01

    Although chromium has been established as an essential trace element for certain animal species, no requirement has been shown for ruminants. Sixteen female lambs (35 kg) were used in an attempt to determine if chromium is essential in the ruminant. Animals were individually housed in all plastic pens and fed twice daily either a low chromium (100 ppb) torula yeast based diet or the basal diet supplemented with 10 ppm chromium as CrCl/sub 3/. Blood samples obtained prior to the morning feeding and 2 and 6 hr post-feeding on days 28 and 56 indicated no significant treatment differences in plasma glucose or serum free fatty acids. By day 56, serum cholesterol tended to be lower in chromium supplemented lambs (60.9 vs 71.7 mg/dl). Lambs in the chromium supplemented treatment also tended to gain more efficiently through 56 days (.130 vs .118 gain/fed). On day 84, lambs were bled after a 48 hr fast, refed, then bled again at 2 and 6 hr post-feeding. Plasma glucose and serum free fatty acids were not affected by chromium at the end of the 48 hr fast or when lambs were refed following fasting. At 84 days both total serum cholesterol and HDL-cholesterol were lower in lambs receiving supplemental chromium. These results suggest that chromium may have a biological role in the ruminant.

  1. Soil washing of chromium- and cadmium-contaminated sludge using acids and ethylenediaminetetra acetic acid chelating agent.

    PubMed

    Gitipour, Saeid; Ahmadi, Soheil; Madadian, Edris; Ardestani, Mojtaba

    2016-01-01

    In this research, the effect of soil washing in the removal of chromium- and cadmium-contaminated sludge samples collected from Pond 2 of the Tehran Oil Refinery was investigated. These metals are considered as hazardous substances for human health and the environment. The carcinogenicity of chromate dust has been established for a long time. Cadmium is also a potential environmental toxicant. This study was carried out by collecting sludge samples from different locations in Pond 2. Soil washing was conducted to treat the samples. Chemical agents, such as acetic acid, ethylenediaminetetra acetic acid (EDTA) and hydrochloric acid, were used as washing solutions to remove chromium and cadmium from sludge samples. The results of this study indicated that the highest removal efficiencies from the sludge samples were achieved using a 0.3 M HCl solution with 82.69% and 74.47% for chromium and cadmium, respectively. EDTA (0.1 M) in the best condition extracted 66.81% of cadmium and 72.52% of chromium from the sludges. The lowest efficiency values for the samples, however, were achieved using 3 M acetic acid with 41.7% and 46.96% removals for cadmium and chromium, respectively. The analysis of washed sludge indicated that the heavy metals removal decreased in the order of 3 M acetic acid < 0.1 M EDTA<0.3 M HCl, thus hydrochloric acid appears to offer a greater potential as a washing agent in remediating the sludge samples.

  2. COST EFFECTIVE CONTROL OF HEXAVALENT CHROMIUM AIR EMISSIONS FROM FUNCTIONAL CHROMIUM ELECTROPLATING

    EPA Science Inventory

    This paper will summrize thie pollution prevention (p2) method to control stack emissions from hard chromium plating operations performed by the USEPA's National Risk Management Research Laboratory (NRMRL) over the last four years. During literature research and user surveys, it...

  3. Electronic and magnetic structure of chromium surfaces and chromium monolayers on iron

    SciTech Connect

    Victora, R.H.; Falicov, L.M.

    1985-05-01

    Chromium surfaces and Cr monolayers atop Fe have greatly enhanced magnetizations relative to bulk. The Cr (100) surface is ferromagnetic with a spin polarization of 3.00; the (110) surface is antiferromagnetic. A Cr monolayer is ferromagnetic atop either the (100) or (110) Fe surfaces; the former has a large polarization of 3.63.

  4. A Laboratory Procedure for the Reduction of Chromium(VI) to Chromium(III).

    ERIC Educational Resources Information Center

    Lunn, George; Sansone, Eric B.

    1989-01-01

    Chromium(VI) compounds are classified as oxidizers and must be specially packaged and transported for disposal while Cr(III) compounds are considered nonoxidizers. A process which reduces Cr(VI) to Cr(III) by adding sodium metabisulfite followed by neutralization with magnesium hydroxide is explored. (MVL)

  5. Diffusion of hexavalent chromium in chromium-containing slag as affected by microbial detoxification.

    PubMed

    Wang, Yunyan; Yang, Zhihui; Chai, Liyuan; Zhao, Kun

    2009-09-30

    An electrochemical method was used to determine the diffusion coefficient of chromium(VI) in chromium-containing slag. A slag plate was prepared from the original slag or the detoxified slag by Achromobacter sp. CH-1. The results revealed that the apparent diffusion coefficient of Cr(VI) was 4.4 x 10(-9)m(2)s(-1) in original slag and 2.62 x 10(-8)m(2)s(-1) in detoxified slag. The results implied that detoxification of chromium-containing slag by Achromobacter sp. CH-1 could enhance Cr(VI) release. Meanwhile, the results of laboratory experiment showed that the residual total Cr(VI) in slag decreased from an initial value of 6.8 mg g(-1) to 0.338 mg g(-1) at the end of the detoxification process. The Cr(VI) released from slag was also reduced by Achromobacter sp. CH-1 strain since water soluble Cr(VI) in the leachate was not detected after 4 days. Therefore, Achromobacter sp. CH-1 has potential application for the bio-detoxification of chromium-containing slag.

  6. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    SciTech Connect

    McCabe, D; Jeff Pike, J; Bill Wilmarth, B

    2007-04-25

    A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions of dollars in clean up and disposal costs. The primary constituents targeted for removal by leaching are aluminum and chromium. It is desirable to have some aluminum in glass to improve its durability; however, too much aluminum can increase the sludge viscosity, glass viscosity, and reduce overall process throughput. Chromium leaching is necessary to prevent formation of crystalline compounds in the glass, but is only needed at Hanford because of differences in the sludge waste chemistry at the two sites. Improving glass formulations to increase tolerance of aluminum and chromium is another approach to decrease HLW glass volume. It is likely that an optimum condition can be found by both performing leaching and improving

  7. Embryo- and fetotoxicity of chromium in pregestationally exposed mice

    SciTech Connect

    Junaid, M.; Murthy, R.C.; Saxena, D.K.

    1996-10-01

    Chromium, an essential element in the human body required for proper carbohydrate, protein, and fat metabolism, is reported to impair gestational development of offspring of workers chronically exposed to this metal in the work place. Workers in chromium based industries can be exposed to concentrations two orders of magnitude higher than the general population. Among the general population, residents living near chromate production sites may be exposed to high levels of chromium (VI) in air or to elevated levels (40 - 50,000 ppm) of chromium in effluents. Shmitova reported afterbirth and puerperal hemorrhages in women industrially exposed to this metal and observed high chromium levels in blood and urine of pregnant women and in fetal and cord blood. Chromium readily passes the placental barrier and reaches the growing fetus. Exposure of mice to chromium during various gestational periods resulted in embryo and fetotoxic effects. This study looks at the role of body chromium accumulated pregestationally on embryo and fetal development and its subsequent transfer to feto-placental sites. 25 refs., 3 tabs.

  8. Chromium and Polyphenols From Cinnamon Improve Insulin Sensitivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Naturally occurring compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in cinnamon. These compounds also have similar effects on insulin signaling and glucose control. The signs of chromium deficiency are similar to those for the metabolic syndrome ...

  9. Safety, absorption, and antioxidant effects of chromium histidine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Supplemental chromium has been shown to be involved in the alleviation of the metabolic syndrome, glucose intolerance, polycystic ovary syndrome, depression, excess body fat, and gestational, steroid-induced, and type 2 diabetes. Chromium amino acid complexes that contained histidine displayed cons...

  10. Processes affecting the remediation of chromium-contaminated sites.

    PubMed Central

    Palmer, C D; Wittbrodt, P R

    1991-01-01

    The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitation/dissolution reactions control the transformation and mobility of chromium. The reduction of CrVI to CrIII can occur in the presence of ferrous iron in solution or in mineral phases, reduced sulfur compounds, or soil organic matter. At neutral to alkaline pH, the CrIII precipitates as amorphous hydroxides or forms complexes with organic matter. CrIII is oxidized by manganese dioxide, a common mineral found in many soils. Solid-phase precipitates of hexavalent chromium such as barium chromate can serve either as sources or sinks for CrVI. Adsorption of CrVI in soils increases with decreasing chromium concentration, making it more difficult to remove the chromium as the concentration decreases during pump-and-treat remediation. Knowledge of these chemical and physical processes is important in developing and selecting effective, cost-efficient remediation designs for chromium-contaminated sites. PMID:1935849

  11. Hydrogel coated fiber Bragg grating based chromium sensor

    NASA Astrophysics Data System (ADS)

    Kishore, P. V. N.; Madhuvarasu, Sai Shankar; Putha, Kishore; Moru, Satyanarayana; Gobi, K. Vengatajalabathy

    2016-04-01

    The present article reports a hydrogel coated Fiber Bragg Grating (FBG) based sensor for chromium metal ion detection. The presence of chromium metal ion in environmental water causes many toxic effects both on humans and animals. The inability of sensing traces of chromium ions is still remains a challenging problem for decades, as the Chromium exists in the environment in different oxidation states. This Paper discusses a chemo-mechanical-optical sensing approach for sensing harmful Chromium ions in environmental water. Fiber Bragg Grating is functionalized with a stimulus responsive hydrogel which swells or deswells depending on ambient chromium ion concentrations. This volume change of the hydrogels causes a bragg shift of the FBG peak. Different peak shifting's, corresponding to different concentrations of the Cr ion concentrations, can be considered as a measure for quantifying traces of chromium ions. Hydrogel network cross-linked with (3-Acrylamidopropyl)-trimethylammonium chloride (ATAC) was synthesized and coated on FBG by dip coating method. Chromium ion concentrations up to ppm (parts per million) can be sensed by this technique.

  12. IRIS Toxicological Review of Hexavalent Chromium (2010 External Review Draft)

    EPA Science Inventory

  1. Biosorption potency of Aspergillus niger for removal of chromium (VI).

    PubMed

    Srivastava, Shaili; Thakur, Indu Shekhar

    2006-09-01

    Aspergillus niger isolated from soil and effluent of leather tanning mills had higher activity to remove chromium. The potency of Aspergillus niger was evaluated in shake flask culture by absorption of chromium at pH 6 and temperature 30 degrees C. The results of the study indicated removal of more than 75% chromium by Aspergillus niger determined by diphenylcarbazide colorimetric assay and atomic absorption spectrophotometry after 7 days. Study of microbial Cr(VI) reduction and identification of reduction intermediates has been hindered by the lack of analytical techniques that can identify the oxidation state with subcellular spatial resolution. Therefore, removal of chromium was further substantiated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), which indicated an accumulation of chromium in the fungal mycelium.

  2. Electroremediation of an industrial area contaminated by chromium.

    PubMed

    Merdoud, O; Akretche, Djamal E

    2008-07-01

    Remediation of soils contaminated by chromium near an industrial area in Algeria has been studied by means of electrokinetic process. Chromium behavior in the course of an electroremediation is studied as a function of the solution in both anolyte and catholyte. After speciation and experiments which consist of 20 days each, it is shown that the use of NaNO(3) in these compartments induces a chromium oxidation by nitrate anion and its removing only through the anion exchange membrane toward the anode. Other ions (Cl(-) and SO(4)(2-) give rise to ion transfer toward the two electrodes showing that the chromium is present at two oxidation states. The pH and the current behavior have also been examined in this work. Results have shown a contribution to the understanding of the removing mechanisms in the course of the electroremediation of a soil contaminated by chromium.

  3. Chromium allergy and dermatitis: prevalence and main findings.

    PubMed

    Bregnbak, David; Johansen, Jeanne D; Jellesen, Morten S; Zachariae, Claus; Menné, Torkil; Thyssen, Jacob P

    2015-11-01

    The history of chromium as an allergen goes back more than a century, and includes an interventional success with national legislation that led to significant changes in the epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium allergy, emphasizing that the investigation of chromium allergy is still far from complete. Our review article on chromium focuses on the allergen's chemical properties, its potential exposure sources, and the allergen's interaction with the skin, and also provides an overview of the regulations, and analyses the epidemiological pattern between nations and across continents. We provide an update on the allergen from a dermatological point of view, and conclude that much still remains to be discovered about the allergen, and that continued surveillance of exposure sources and prevalence rates is necessary.

  4. The Theory for the Mechanism of Chromium Plating: The Theory for the Physical Characteristics of Chromium Plate

    DTIC Science & Technology

    1947-01-01

    deposits arc pro- duced as the coll potential is successively raised. The sulfato ion "hus has an extremely important effect in the chromium plating...and sulfato iDU in the bath wore then used in an attempt to obtain more satisfactory hexagonal chromium deposits. The data obtained are summarUod

  5. Determination of chromium in treated crayfish, Procambarus clarkii, by electrothermal ASS: study of chromium accumulation in different tissues

    SciTech Connect

    Hernandez, F.; Diaz, J.; Medina, J.; Del Ramo, J.; Pastor, A.

    1986-06-01

    In the present study, the authors investigated the accumulation of chromium in muscle, hepatopancreas, antennal glands, and gills of Procambarus clarkii (Girard) from Lake Albufera following Cr(VI)-exposure. Determinations of chromium were made by using Electrothermal Atomic Absorption Spectroscopy and the standard additions method.

  6. Reaction of chromium(VI) with glutathione or with hydrogen peroxide: Identification of reactive intermediates and their role in chromium(VI)-induced DNA damage

    SciTech Connect

    Aiyar, J.; Berkovits, H.J.; Wetterhahn, K.E. ); Floyd, R.A. )

    1991-05-01

    The types of reactive intermediates generated upon reduction of chromium (VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium (VI) with glutathione led to formation of two chromium (V) complexes and the glutathione thiyl radical. When chromium (VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chromium (V) formation. Reaction of chromium (VI) with hydrogen peroxide led to formation of hydroxyl radical. No chromium (V) was detectable at 24 C (297 K); however, low levels of the tetraperoxochromium (V) complex were detected at 77 K. Reaction of chromium (VI) with DNA in the presence of hydrogen peroxide produced significant DNA strand breakage and the 8-hydroxydeoxyguanosine adduct, whose formation correlated with hydroxyl radical production. No significant chromium-DNA adduct formation was detected. Thus, the nature of chromium (VI)-induced DNA damage appears to be dependent on the reactive intermediates, i.e., chromium (V) or hydroxyl radical, produced during the reduction of chromium (VI).

  7. Occupational asthma induced by chromium salts.

    PubMed

    Olaguibel, J M; Basomba, A

    1989-01-01

    Five patients with asthma related to exposure to chromium salts, in their work area, are presented. All of them were non atopics and presented a history of contact dermatitis, with positive patch tests to potassium dichromate, previous to the onset of bronchial asthma. Solutions of K2Cr2O5 were prepared in normal saline at 0.01, 0.1 and 1 mg/ml for skin prick tests (SPT) and bronchial provocation tests (BPT). Immediate cutaneous reaction by SPT was negative for controls and patients. BPT were performed by the tidal breathing method, with positive results in all subjects. A negative response was recorded in 4 control unexposed asthmatics. An attempt to inhibit BPT with sodium cromoglycate was unsuccessful. The diversity of reactions (immediate, dual and late) registered in BPT, support that bronchial reactivity can be induced specifically by inhalation of chromium salts. The data of follow-up indicates a good prognosis, provided that patients remain out of exposure. The lack of facts suggesting an IgE-mediated reaction puts forward for consideration other pathophysiologic mechanisms.

  8. 76 FR 71926 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-21

    ... Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to Commercial Items (DFARS Case... hexavalent chromium. DATES: Comment Date: Comments on the proposed rule should be submitted in writing to the... chromium. Hexavalent chromium is a chemical that has been used in numerous DoD weapons systems...

  9. 75 FR 65067 - National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-21

    ... Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and Resins; Marine Tank...: Hard and Decorative Chromium Electroplating and Chromium Anodizing Tanks; Group I Polymers and Resins... Tanks. Group I Polymers and Resins Production.. Scott Throwe, (202) 564-7013,...

  10. Chromium absorption in the vascularly perfused rat intestine

    SciTech Connect

    Dowling, H.J.; Offenbacher, E.G.; Pi-Sunyer, F.X.

    1986-03-01

    The mechanism of chromium (Cr) absorption by the rat small intestine was investigated using a double perfusion technique wherein the luman of the small intestine and the vasculature supplying it were separately perfused. The intestinal perfusate (IP) was a nutrient-rich tissue culture medium (TCM) with added inorganic Cr and /sup 51/Cr. The vascular perfusate (VP) was a Krebs-Ringer bicarbonate solution (KRB) containing 4.7% dextran, 0.1% glucose and 5% human serum. Cr absorption was calculated by the amount of /sup 51/Cr detected in the VP. To determine the transport mechanism for Cr, its absorption into the VP was measured at various Cr concentrations of the IP ranging from 10-400 ppb CrCl/sub 3/. The amount of Cr absorbed into the blood rose linearly with the intestinal Cr concentration suggesting a process of simple diffusion. Manipulations of the VP and IP constituents were made to investigate their effects on Cr absorption. When serum was omitted from the VP, Cr adsorption was suppressed, suggesting that serum component(s) are necessary for optimal Cr absorption. When either of 2 plasma transport proteins (apo-transferrin, albumin) were added to the serum-free VP at physiological levels, Cr absorption returned to, but did not exceed, control levels. When the TCM was replaced with a KRB solution; Cr absorption was suppressed indicating that there are nutrient(s) of the TCM which facilitate Cr absorption. Further suppression occurred when a Cr concentration gradient opposing Cr absorption was created (IP at 100 ppb Cr, VP at 400 ppb Cr).

  11. Workshop on effects of chromium coating on Nb{sub 3}Sn superconductor strand: Proceedings

    SciTech Connect

    Not Available

    1994-04-12

    This report discusses the following topics: Chromium coating on superconductor strand -- an overview; technology of chromium plating; comparison of wires plated by different platers; search for chromium in copper; strand manufactures` presentations; chromium plating at the Lawrence Livermore National Laboratory; a first look at a chromium plating process development project tailored for T.P.X. and I.T.E.R. strand; and influence of chromium diffusion and related phenomena on the reference ratios of bare and chromium plated Nb{sub 3}Sn strand.

  12. Mode of occurrence of chromium in four US coals

    USGS Publications Warehouse

    Huggins, Frank E.; Shah, N.; Huffman, G.P.; Kolker, A.; Crowley, S.; Palmer, C.A.; Finkelman, R.B.

    2000-01-01

    The mode of occurrence of chromium in three US bituminous coals and one US subbituminous has been examined using both X-ray absorption fine structure (XAFS) spectroscopy and a selective leaching protocol supplemented by scanning electron microscopy (SEM) and electron microprobe measurements. A synthesis of results from both methods indicates that chromium occurs principally in two forms in the bituminous coals: the major occurrence of chromium is associated with the macerals and is not readily leached by any reagent, whereas a second, lesser occurrence, which is leachable in hydrofluoric acid (HF), is associated with the clay mineral, illite. The former occurrence is believed to be a small particle oxyhydroxide phase (CrO(OH)). One coal also contained a small fraction (<5%) of the chromium in the form of a chromian magnetite, and the leaching protocol indicated the possibility of a similar small fraction of chromium in sulfide form in all three coals. There was little agreement between the two techniques on the mode of occurrence of chromium in the subbituminous coal; however, only a limited number of subbituminous coals have been analyzed by either technique. The chromium in all four coals was trivalent as no evidence was found for the Cr6+ oxidation state in any coal.

  13. Lipid peroxidation in workers exposed to hexavalent chromium.

    PubMed

    Huang, Y L; Chen, C Y; Sheu, J Y; Chuang, I C; Pan, J H; Lin, T H

    1999-02-26

    The aim of this study was to investigate whether exposure to hexavalent chromium induces lipid peroxidation in human. This study involved 25 chrome-plating factory workers and a reference group of 28 control subjects. The whole-blood and urinary chromium concentrations were determined by graphite furnace atomic absorption spectrophotometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography, and the activities of protective enzymes were measured by ultraviolet-visible spectrophotometry. In the chrome-plating workers, the mean concentrations of chromium in blood and urine were 5.98 microg/L and 5.25 microg/g creatinine, respectively; the mean concentrations of MDA in blood and urine were 1.7 micromol/L and 2.24 micromol/g creatinine. The concentrations of both chromium and MDA in blood and urine were significantly higher in the chromium-exposed workers. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) were not markedly different between control and exposed workers. Data suggest that MDA may be used as a biomarker for occupational chromium exposure. Antioxidant enzymic activities are not a suitable marker for chromium exposure.

  14. Removal of chromium from tannery effluents by adsorption.

    PubMed

    Fadali, O A; Magdy, Y H; Daifullah, A A M; Ebrahiem, E E; Nassar, M M

    2004-01-01

    Tannery effluent is characterized not only by heavy loads but also with toxic heavy metals especially chromium ions. Chromium is considered an important source of contamination due to large volume of exhaust liquid discharged and solid sludge produced. Details on adsorption studies were carried out using synthetic chromium salts (chromium chloride) as adsorbate, and cement kiln dust (a waste from white cement industry) as adsorbent. Equilibrium isotherms have been determined for the adsorption of chromium ions on cement kiln dust. Kinetic study provided that the adsorption process is diffusion controlled. The experimental results have been fitted using Freundlich, Langmuir, and Redlich Peterson isotherms. The maximum adsorption capacity of cement kiln dust was found to be 33 mg/g. Industrial tannery effluent (22-mg/L chromium and COD 952 mg/L) was also treated by cement dust. The treated effluent (using 20 g cement dust per 1 L) contains only 0.6 mg/L chromium and COD 200 mg/L.

  15. Controlling diabetes by chromium complexes: The role of the ligands.

    PubMed

    Peng, Mei; Yang, Xiaoping

    2015-05-01

    Diabetes, particularly type II diabetes, is a severe disease condition which affects human health worldwide, with a dramatically increasing trend in Asian countries including China. Currently, no efficient drugs other than those with observable side effects are available. Chromium complexes, with the most known representative chromium picolinate, have been listed as one of most attractive health supplements to attenuate this disease condition in western countries. Recent efforts have been made to develop new chromium complexes with novel ligands. Although fair amounts of reviews have been published to emphasize the biological activity, preclinical and clinical information of chromium picolinate, this mini-review is trying to cover the entire picture of updated research efforts on various chromium complexes highlighting the role of ligands. Chromium phenylalanine sensitizes insulin cell signaling pathway via the activation of phosphorylation of Akt (protein kinase B (PKB)) and/or AMPK (AMP-activated protein kinase). The biological activities, toxicity, pharmacological features and clinical implications, including the effect of anti-oxidative capacities, protective effect on obese-induced heart dysfunction, and efficacy and safety of chromium supplementation in diabetes are discussed as well.

  16. Chromium isotopes and the fate of hexavalent chromium in the environment

    USGS Publications Warehouse

    Ellis, Andre S.; Johnson, Thomas M.; Bullen, Thomas D.

    2002-01-01

    Measurements of chromium (Cr) stable-isotope fractionation in laboratory experiments and natural waters show that lighter isotopes reacted preferentially during Cr(VI) reduction by magnetite and sediments. The 53Cr/52Cr ratio of the product was 3.4 ± 0.1 per mil less than that of the reactant.53Cr/52Cr shifts in water samples indicate the extent of reduction, a critical process that renders toxic Cr(VI) in the environment immobile and less toxic.

  17. Spectroscopic analysis of chromium bioremediation products

    NASA Astrophysics Data System (ADS)

    Varadharajan, C.; Nico, P. S.; Yang, L.; Marcus, M. A.; Steefel, C.; Larsen, J. T.; Beller, H. R.; Brodie, E. L.

    2010-12-01

    Remediation of chromium contamination frequently involves reducing the toxic and soluble hexavalent form, Cr(VI), to the relatively harmless and mostly immobile trivalent state, Cr(III). The objective of this study is to identify the biogeochemical reactions that control in situ chromium reduction in the presence of different dominant electron acceptors, i.e., NO3-, Fe(III), and SO42-. It was hypothesized that indirect, abiotic reduction of Cr(VI) by reduced metabolic products [Fe(II) and sulfides] would dominate over direct enzymatic reduction by denitrifying, iron-reducing, or sulfate-reducing bacteria. It is further hypothesized that the enzymatic reduction of Cr(VI) would produce relatively pure chromium hydroxide precipitates, whereas indirect reduction would result in mixed Cr-Fe hydroxide solid phases. Flow-through columns containing homogenized sediments from the 100H site at Hanford, WA were subjected to nitrate-, sulfate- or iron-reducing conditions in the presence of 5 µM Cr(VI) and 5 mM lactate. Cr(VI) was depleted in the effluent solutions from the nitrate- and sulfate-reducing columns; however only a small amount of Cr(VI) was removed under iron-reducing conditions. Preliminary analysis of micro X-ray absorption spectra indicate that the untreated and iron-reducing column sediments contained pre-existing Cr in the form of primary minerals, e.g. chromite and/or Cr-bearing micas. However, there was an increase in the relative abundance of mixed-phase Cr-Fe hydroxides, i.e., Cr1-xFex(OH)3 in the nitrate- and sulfate-treated columns. A possible explanation for the observations is that the production of Fe(II) was enhanced under the nitrate- and sulfate- reducing conditions, and was most likely sulfide-driven in the latter case. The Fe(II) was subsequently available for reduction of Cr(VI) resulting in the mixed-phase precipitates. The results from the spectroscopic analysis support the hypothesis that Fe(II)-mediated Cr reduction prevails over direct

  18. Oral bioaccessibility of trivalent and hexavalent chromium in soil by simulated gastric fluid.

    PubMed

    Skowronski, G A; Seide, M; Abdel-Rahman, M S

    2001-07-06

    Chromium is found in soil from natural sources and anthropogenic activities. The ingestion of soil contaminated with chromium especially by children can have toxic consequences. Therefore, it is important to quantify the oral bioaccessibility of chromium in chromium in contaminated soil. In this study, chromium-51 as chromic (III) chloride and sodium chromate (VI), was mixed with an Atsion sandy soil and a Keyport clay soil and stored for 4 mo at either 21-25 degrees C or 2-4 degrees C. Utilizing simulated gastric conditions, the oral bioaccessibility of chromium in soil was determined. When the effects of soil on the bioaccessibility of chromium were compared, the data revealed the the bioaccessibility of chromium (III) from the clay soil was significantly lower than from the sandy at 21-25 degrees C. However, at 2-4 degrees C, more chromium (III) was extracted by synthetic gastric fluid from the clay soil than from the sandy soil. Temperature was also a factor as evidenced by the higher bioaccessibility of chromium (IV) in the sandy soil at 2-4 degrees C and of both chromium species in the clay soil at the same temperature. Reduction of the soluble chromium (VI) chemical to the nonsoluble chromium (III) compound in the acidic soils by naturally occurring organic matter in soil would explain the lower bioaccessibilty of chromium (VI) at 21-25 degrees C. At 2-4 degrees C, the data indicate that the rate of chromium (VI) reduction to chromium (III) was slowed. Although the results of this study are limited to one low concentration of chromium (III) and chromium (VI) and indicate that the bioaccessibility of chromium in soil can range between 18% and 72%, the data also suggest that there may be a potential health hazard from oral exposure to chromium in heavily contaminated sites. Therefore, more extensive research should be conducted to determine if thes findings can be extended to environmentally relevant concentrations.

  19. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria

    NASA Astrophysics Data System (ADS)

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L-1.

  20. [Blood and urine chromium: compared values between chromium exposed workers and common people].

    PubMed

    Provenzani, A; Verso, M G; Picciotto, D

    2008-01-01

    Aim of present study is the valutation and quantification of chromium in blood and urine. We compared 3 groups of persons formed by building workers, in particular masons, because cement contains potassium chromate that is dangerous for health, and by common people: urban population and outside the town population. In fact, exposure to CrVI risk is high for people who live near chromate industries. We maked a medical examination, blood and instrumental tests, chromium measuring in blood (recent exposure indicator) and urine (recent and previous indicator). Then we used statistical methods to estimate obtained values of blood and urine chromium among professional exposed people and common people. At the end we think that preventive measures in working environment reduced exposure to CrVI but environmental exposure (for example road dust from catalytic converter erosion, from brake lining erosion, cement dust and tobacco smoke), in the last years, has increased. So there are no difference between urban population and outside the town population and there are also no difference with professional exposed people for work prevention according to law in force, that let down professional risk using safe limits.

  1. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria.

    PubMed

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L(-1).

  2. Evaluation of chromium in red blood cells as an indicator of exposure to hexavalent chromium: An in vitro study.

    PubMed

    Devoy, Jérôme; Géhin, Antoine; Müller, Samuel; Melczer, Mathieu; Remy, Aurélie; Antoine, Guillaume; Sponne, Isabelle

    2016-07-25

    Chromium(VI) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and whole blood (i.e., including plasma) are indicative of recent exposure, chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure. Before recommending Cr in RBC as a biological indicator of Cr(VI) exposure, in-vitro studies must be undertaken to assess its reliability. The present study examines the relationship between the chromium added to a blood sample and that subsequently found in the RBC. After incubation of total blood with chromium, RBC were isolated, counted and their viability assessed. Direct analysis of chromium in RBC was conducted using Atomic Absorption Spectrometry. Hexavalent, but not trivalent Cr, was seen to accumulate in the RBC and we found a strong correlation between the Cr(VI) concentration added to a blood sample and the amount of Cr in RBC. This relationship appears to be independent of the chemical properties of the human blood samples (e.g., different blood donors or different reducing capacities). Even though in-vivo studies are still needed to integrate our understanding of Cr(VI) toxicokinetics, our findings reinforce the idea that a single determination of the chromium concentration in RBC would enable biomonitoring of critical cases of Cr(VI) exposure.

  3. Pyrolysis of chromium rich tanning industrial wastes and utilization of carbonized wastes in metallurgical process.

    PubMed

    Tôrres Filho, Artur; Lange, Liséte Celina; de Melo, Gilberto Caldeira Bandeira; Praes, Gustavo Eduardo

    2016-02-01

    Pyrolysis is the thermal degradation of organic material in oxygen-free or very lean oxygen atmosphere. This study evaluates the use of pyrolysis for conversion of leather wastes from chromium tanning processes into Carbonized Leather Residues (CLR), and the utilization of CLR in metallurgical processes through the production of iron ore pellets. CLR was used to replace mineral coal in proportions of 10% and 25% on fixed carbon basis content in the mixtures for pellets preparation. Experimental conversions were performed on a pilot scale pyrolysis plant and a pelletizing reactor of the "pot grate" type. The results demonstrated the technical feasibility of using the charcoal product from animal origin as an energy source, with recovery of up to 76.47% of chromium contained in CLR in the final produced of iron ore pellets. Pellets with 25% replacement of fixed carbon in the coal showed an enhanced compressive strength, with an average value of 344kgfpellet(-1), compared to 300kgfpellet(-1) for standard produced pellets.

  4. Metabolic reduction of chromium by alveolar macrophages and its relationships to cigarette smoke.

    PubMed Central

    Petrilli, F L; Rossi, G A; Camoirano, A; Romano, M; Serra, D; Bennicelli, C; De Flora, A; De Flora, S

    1986-01-01

    Pulmonary alveolar macrophages (PAM), obtained by bronchoalveolar lavage from 47 individuals, reduced hexavalent chromium [Cr(VI)] and decreased its mutagenicity. Their specific activity--mostly mediated by cytosolic, enzyme-catalyzed mechanisms--was significantly higher than in corresponding preparations of mixed-cell populations from human peripheral lung parenchyma or bronchial tree, or from rat lung or liver. At equivalent number of PAM, Cr(VI) reduction, total protein, and some oxidoreductase activities were significantly increased in smokers. No appreciable variation could be detected between lung cancer and noncancer patients. In rats, the Cr(VI)-reducing activity of PAM preparations was induced by Aroclor 1254. Thus, alveolar macrophages provide crucial defense mechanisms not only by phagocytizing metals, but also by metabolically reducing Cr(VI). The epithelial-lining fluid (ELF) also displayed some Cr(VI) reduction. Together with already investigated metabolic processes occurring inside lung cells, these mechanisms are expected to determine thresholds in the pulmonary carcinogenicity of chromium. PMID:2423559

  5. Increased chromium and nickel content in lung tissue and bronchial carcinoma

    SciTech Connect

    Kollmeier, H.; Seemann, J.W.; Mueller, K.M.R.; Rothe, G.; Wittig, P.; Schejbal, V.B.

    1987-01-01

    In 25 random autopsies, chromium (Cr) and nickel (Ni) in lung tissue and regional lymph nodes were analysed by means of flameless atomic absorption spectrometry (AAS). The subjects originate from Bochum in the Ruhr District, which is defined as a particular pollution area with locally high Cr and Ni emissions. The subjects examined from Bochum (BO) and vicinity have Cr and Ni concentrations about 5 and 6 times higher than those in a previous series form Muenster (MS) and vicinity (outside the particular pollution area), which is used for comparison purposes. BO and MS data showed an age-dependent increase of chromium and nickel in the lung, and in both data sets as well as in the combined, the Cr and Ni values showed extremely high correlations. The Cr and Ni concentrations (BO) in lung (3.47 +/- 2.53 micrograms Cr/g, 1.09 +/- 1.43 micrograms Ni/g dry weight) and lymph node tissue (6.30 +/- 3.72 micrograms Cr/g, 1.00 +/- 0.58 micrograms Ni/g dry weight) do not show any correlation. The BO data contained four cases of bronchial carcinoma (all male), three of which showed pulmonary Cr and Ni concentrations that lie clearly above the predicted level. One case of bronchial carcinoma had extremely high Cr and Ni values; an occupational exposure as dental laboratory technician is taken into consideration.

  6. Possible adverse effect of chromium in occupational exposure of tannery workers.

    PubMed

    Kornhauser, Carlos; Wróbel, Katarzyna; Wróbel, Kazimierz; Malacara, Juan Manuel; Nava, Laura Eugenia; Gómez, Leobardo; González, Rita

    2002-04-01

    Our aim was to investigate the adverse effects of occupational exposure to trivalent chromium. We measured chromium and iron levels in serum and urine and hemoglobin levels in tannery workers and unexposed persons. We studied three groups of subjects. Group 1 included 15 non-smoking male tannery workers highly exposed to chromium from tanning and retanning departments. Group 2 included 14 non-smoking male tannery workers with moderate chromium exposure from dying, drying and finishing departments. Group 3 included 11 healthy, non-smoking male subjects without direct chromium exposure. Higher serum chromium levels were observed in groups 1 and 2 with respect to group 3 (mean values respectively: 0.43; 0.25 and 0.13 microg x l(-1)). Urine chromium levels in group 1 were higher than those in controls (mean values: 1.78 and 1.35 microg x l(-1)). In group 1 an inverse association was found between serum chromium and urine iron (-0.524), urine chromium and hemoglobin (-0.594) and between the urine chromium to iron ratio and hemoglobin (-0.693, p<0.05). The results suggest a chromium adverse effect on iron metabolism, possibly associated with excessive body chromium accumulation. In conclusion, chromium urine test could be recommended for diagnosis of chromium adverse effect on iron metabolism. Further studies are needed to quantify the relationship between urine chromium and hemoglobin metabolism.

  7. TiC reinforced cast chromium steels

    SciTech Connect

    Dogan, Omer N.; Rawers, James C.; Hawk, Jeffrey A.; Schrems, Karol K.

    2003-11-01

    A series of new titanium carbide reinforced cast chromium steels were developed for wear applications. Objective of the program was to enhance wear resistant alloys and, if possible, improve mechanical properties. The new steels which were melted in a vacuum induction furnace contained 12 Cr, 3-5 Ti, 1-2 C in weight percent. Alloying with Ti changed the precipitate microstructure from Cr carbide to TiC dispersed in a martensitic matrix. Yield strength and impact resistance improved with Ti alloying. Wear rates of the cast Cr/TiC steels, (determined from high- and low-stress abrasion tests, erosion test, and scratch tests) were generally lower than both the as-cast and heat-treated AISI type 440°C steel and were often further reduced by increasing the Ti alloy concentration. The exceptions were the erosion test for which all materials had similar wear rate.

  8. Chromium detoxification by fixed-film bioreactors

    SciTech Connect

    Chirwa, E.M.N.; Wang, Y.T.

    1996-11-01

    In this study, completely mixed, continuous flow bioreactors were utilized to detoxify chromium. Glass beads were incorporated as a support medium for two strains of bacteria, Bacillus sp. and Pseudomonas fluorescens LB300 (LB300), growing aerobically in two separate reactors. Aerobic conditions were maintained in the reactors by continuously supplying fresh air to the liquid through gas exchange chambers installed on the recycle line of the bioreactors. Results obtained showed that near complete removal of chromate was possible for influent concentrations up to 200 mg/L for Bacillus sp., and up to 100 mg/L for LB300 at 24 hours liquid detention time. Similar results were obtained for corresponding loading rates at 12 hours and 6 hours liquid detention time.

  9. Self-Lubricating Composite Containing Chromium Oxide

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher (Inventor); Edmonds, Brian J. (Inventor)

    1999-01-01

    A self lubricating. friction and wear reducing composite material useful over a wide temperature range of from cryogenic temperature up to about 900 C. contains 60 80 wt. % of particulate Cr2O3, dispersed in a metal binder of a metal alloy containing Cr and at least 50 wt. % of Ni, Cr or a mature of Ni and Cr. It also contains 5-20 wt. % of a fluoride of at least one Group I, Group II or rare earth metal and. optionally, 5-20 wt. % of a low temperature lubricant metal, such as Ag. Au, Pt, Pd, Rh and Cu. This composite exhibits less oxidation instability and less abrasiveness than composites containing chromium carbide, is readily applied using plasma spray and can be ground and polished with a silicon carbide abrasive.

  10. Chromium concentrations in ruminant feed ingredients.

    PubMed

    Spears, J W; Lloyd, K E; Krafka, K

    2017-02-22

    Chromium (Cr), in the form of Cr propionate, has been permitted for supplementation to cattle diets in the United States at levels up to 0.50 mg of Cr/kg of DM since 2009. Little is known regarding Cr concentrations naturally present in practical feed ingredients. The present study was conducted to determine Cr concentrations in feed ingredients commonly fed to ruminants. Feed ingredients were collected from dairy farms, feed mills, grain bins, and university research farms. Mean Cr concentrations in whole cereal grains ranged from 0.025 mg/kg of DM for oats to 0.041 mg/kg of DM for wheat. Grinding whole samples of corn, soybeans, and wheat through a stainless steel Wiley mill screen greatly increased analyzed Cr concentrations. Harvested forages had greater Cr concentrations than concentrates, and alfalfa hay or haylage had greater Cr concentrations than grass hay or corn silage. Chromium in alfalfa hay or haylage (n = 13) averaged 0.522 mg/kg of DM, with a range of 0.199 to 0.889 mg/kg of DM. Corn silage (n = 21) averaged 0.220 mg of Cr/kg of DM with a range of 0.105 to 0.441 mg of Cr/kg of DM. By-product feeds ranged from 0.040 mg of Cr/kg of DM for cottonseed hulls to 1.222 mg of Cr/kg of DM for beet pulp. Of the feed ingredients analyzed, feed grade phosphate sources had the greatest Cr concentration (135.0 mg/kg). Most ruminant feedstuffs and feed ingredients had less than 0.50 mg of Cr/kg of DM. Much of the analyzed total Cr in feed ingredients appears to be due to Cr contamination from soil or metal contact during harvesting, processing, or both.

  11. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Generated by Manufacturers or Users of Nickel, Chromium, or Iron Baghouse bags Raney nickel catalyst Floor... Nickel, chromium, and iron catalysts Nickel-cadmium and nickel-iron batteries Filter cake from...

  12. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Generated by Manufacturers or Users of Nickel, Chromium, or Iron Baghouse bags Raney nickel catalyst Floor... Nickel, chromium, and iron catalysts Nickel-cadmium and nickel-iron batteries Filter cake from...

  13. 40 CFR Appendix Xii to Part 266 - Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Generated by Manufacturers or Users of Nickel, Chromium, or Iron Baghouse bags Raney nickel catalyst Floor... Nickel, chromium, and iron catalysts Nickel-cadmium and nickel-iron batteries Filter cake from...

  14. Effects of Chromium(VI) and Chromium(III) on Desulfovibrio vulgaris Cells

    SciTech Connect

    M.E. Clark; A. Klonowska; S.B. Thieman; B. Giles; J.D. Wall; and M.W. Fields

    2007-04-19

    Desulfovibrio vulgaris ATCC 29579 is a well studied sulfate reducer that has known capabilities of reducing heavy metals and radionuclides, like chromium and uranium. Cultures grown in a defined medium (i.e. LS4D) had a lag period of approximately 40 h when exposed to 50 μMof Cr(VI). Substrate analysis revealed that although chromium is reduced within the first 5 h, growth does not resume for another 35 h. During this time, small amounts of lactate are still utilized but the reduction of sulfate does not occur. Sulfate reduction occurs concurrently with the accumulation of acetate approximately 40 h after inoculation, when growth resumes. Similar amounts of hydrogen are produced during this time compared to hydrogen production by cells not exposed to Cr(VI); therefore an accumulation of hydrogen cannot account for the utilization of lactate. There is a significant decrease in the carbohydrate to protein ratio at approximately 25 h, and this result indicated that lactate is not converted to glycogen. Most probable number analysis indicated that cell viability decreased steadily after inoculation and reached approximately 6 x 104 cells/ml 20 h post-chromium exposure. Regeneration of reducing conditions during chromium exposure does not induce growth and in fact may make the growth conditions even more unfavorable. This result suggested that an increase in Eh was not solely responsible for the decline in viability. Cell pellets collected 10 h after chromium-exposure were unable to resume growth when suspended into fresh medium. Supernatants from these pellets were able to support cell growth upon re- inoculation. D. vulgaris cells treated with a non-dose dependent addition of ascorbate at the same time of Cr(VI) addition did not enter a lag period. Ascorbate added 3 h post-Cr(VI) exposure did not prevent the growth lag. These results indicated that Desulfovibrio utilized lactate to reduce Cr(VI) without the reduction of sulfate, that the decline in cell viability and

  15. USE OF FUME SUPPRESSANTS IN HARD CHROMIUM BATHS - QUALITY TESTING

    EPA Science Inventory

    The EPA Common Sense Initiative (CSI) is a cooperative effort of government, industry, environmental and other stakeholder groups to find "cleaner, cheaper, smarter" approaches to environmental management in industrial sectors. The purpose of the project is to help hard chromium ...

  16. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...), not more than 30 parts per million. Arsenic (as As), not more than 3 parts per million. Total oxides of aluminum, chromium, and cobalt not less than 97 percent. Lead and arsenic shall be determined...

  17. IRIS Toxicological Review of Hexavalent Chromium (Peer Review Plan)

    EPA Science Inventory

    EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessment of hexavalent chromium that will appear on the Integrated Risk Information System (IRIS) database.

  18. Chromium and Polyphenols from Cinnamon and Insulin Sensitivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Factors that improve insulin sensitivity usually lead to improvements in risk factors associated with the metabolic syndrome, diabetes, and cardiovascular diseases. Naturally occurring bioactive compounds that have been shown to improve insulin sensitivity include chromium and polyphenols found in ...

  19. [Occupational diseases caused by chromium and its compounds].

    PubMed

    Hassmanová, V; Vanĕcková, J; Bousová, K

    2000-01-01

    The present paper demonstrates by documentary evidence occupational diseases caused by chromium and its compounds. Perforations of the nasal septum were diagnosed in 20 males and 9 females, the last one in 1980. Most of them worked in chromium-plating shops. Other diseases, including bronchial asthma, allergic rhinitis, and contact allergic eczemas, were examined in 1985-1999. Bronchial asthma was reported in a textile dyer who was in contact with chromium dyes for 32 years and two allergic rhinitides (a welder and an electroplater) were reported in 1987 as "other damage to health resulting from work." Out of 103 contact allergic eczemas, only 24 diseases, i.e. less than one quarter, were healed in 1999. Improvements were observed in 59 of them and 20 diseases persist. There was an exceptional finding of a chromium ulcer (pigeonneaux) on the lower extremity of a builder.

  20. Chromium plating pollution source reduction by plasma source ion implantation

    SciTech Connect

    Chen, A.; Sridharan, K.; Dodd, R.A.; Conrad, J.R.; Qiu, X.; Hamdi, A.H.; Elmoursi, A.A.; Malaczynski, G.W.; Horne, W.G.

    1995-12-31

    There is growing concern over the environmental toxicity and workers` health issues due to the chemical baths and rinse water used in the hard chromium plating process. In this regard the significant hardening response of chromium to nitrogen ion implantation can be environmentally beneficial from the standpoint of decreasing the thickness and the frequency of application of chromium plating. In this paper the results of a study of nitrogen ion implantation of chrome plated test flats using the non-line-of-sight Plasma Source Ion Implantation (PSII) process, are discussed. Surface characterization was performed using Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), and Electron Spectroscopy for Chemical Analysis (ESCA). The surface properties were evaluated using a microhardness tester, a pin-on-disk wear tester, and a corrosion measurement system. Industrial field testing of nitrogen PSII treated chromium plated parts showed an improvement by a factor of two compared to the unimplanted case.

  1. The effect of chromium oxyhydroxide on solid oxide fuel cells.

    SciTech Connect

    Krumpelt, M.; Cruse, T. A.; Ingram, B. J.; Routbort, J. L.; Wang, S.; Salvador, P. A.; Chen, G.; Carnegie Mellon Univ.; NETL; Ohio Univ.

    2010-01-01

    Hexavalent chromium species like the oxyhydroxide, CrO{sub 2}(OH){sub 2}, or hexoxide, CrO{sub 3}, are electrochemically reduced to Cr{sub 2}O{sub 3} in solid oxide fuel cells and adversely affect the cell operating potentials. Using a narrowly focused beam from the Advanced Photon Source, such chromium oxide deposits were unequivocally identified in the active region of the cathode by X-ray diffraction, suggesting that the triple phase boundaries were partially blocked. Under fuel cell operating conditions, the reaction has an equilibrium potential of about 0.9 V and the rate of chromium oxide deposition is therefore dependent on the operating potential of the cell. It becomes diffusion limited after several hours of steady operation. At low operating potentials, lanthanum manganite cathodes begin to be reduced to MnO, which reacts with the chromium oxide to form the MnCr{sub 2}O{sub 4} spinel.

  2. SCIENCE AND TECHNOLOGY ACTIVITIES FOR CHROMIUM IN THE 100 AREAS

    SciTech Connect

    PETERSEN SW

    2009-07-02

    {sm_bullet} Primary Objective: Protect the Columbia River - Focus is control and treatment of contamination at or near the shoreline, which is influenced by bank storage {sm_bullet} Secondary Objective: Reduce hexavalent chromium to <48 parts per billion (ppb) in aquifer (drinking water standard) - Large plumes with isolated areas of high chromium concentrations (> 40,000 ppb), - Unknown source location(s); probably originating in reactor operation areas

  3. Electrodeposition of amorphous ternary nickel-chromium-phosphorus alloy

    DOEpatents

    Guilinger, Terry R.

    1990-01-01

    Amorphous ternary nickel-chromium-phosphorus alloys are electrodeposited from a bath comprising a nickel salt, a chromium salt, a phosphorus source such as sodium hypophosphite, a complexing agent for the nickel ions, supporting salts to increase conductivity, and a buffering agent. The process is carried out at about room temperature and requires a current density between about 20 to 40 A/dm.sup.2.

  4. Chromium (V) compounds as cathode material in electrochemical power sources

    DOEpatents

    Delnick, Frank M.; Guidotti, Ronald A.; McCarthy, David K.

    1985-01-01

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca.sub.5 (CrO.sub.4).sub.3 Cl, Ca.sub.5 (CrO.sub.4).sub.3 OH, and Cr.sub.2 O.sub.5. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  5. Chromium Ions Improve Moisure Resistance of Epoxy Resins

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; St. Clair, T. L.; Stoakley, D. M.; Singh, J. J.; Sprinkle, D. R.

    1986-01-01

    Broad spectrum of thermosetting epoxy resins used on commercial and military aircraft, primarily as composite matrices and adhesives. In new technique, chromium-ion containing epoxy with improved resistance to moisture produced where chromium ions believed to prevent absorption of water molecules by coordinating themselves to hydroxyl groups on epoxy chain. Anticipated that improved epoxy formulation useful as composite matrix resin, adhesive, or casting resin for applications on commercial and advanced aircraft. Improvement made without sacrifice in mechanical properties of polymer.

  6. Chromium (V) compounds as cathode material in electrochemical power sources

    DOEpatents

    Delnick, F.M.; Guidotti, R.A.; McCarthy, D.K.

    A cathode for use in a thermal battery, comprising a chromium (V) compound. The preferred materials for this use are Ca/sub 5/(CrO/sub 4/)/sub 3/Cl, Ca/sub 5/(CrO/sub 4/)OH, and Cr/sub 2/O/sub 5/. The chromium (V) compound can be employed as a cathode material in ambient temperature batteries when blended with a suitably conductive filler, preferably carbon black.

  7. Sludge Generation from Ferrous/Sulfide Chromium Treatment.

    DTIC Science & Technology

    1984-08-01

    sodium bisulfite , sulfur dioxide, and sodium sulfide. While all these chemicals produce a satisfactory effluent, the quantity of sludge produced by the...34Treatment of Toxic Metal Wastewaters by Alkaline Ferrous Sulfate and Sodium Sulfied for Chromium Reduction, Precipitation and Coagulation," Pro... sodium sulfide and ferrous chloride (9:1 ratio) at pH 8.0 rapidly reduced hexavalent chromium and produced approximately one-fourth the sludge (on a

  8. Removal of chromium from industrial waste by using eucalyptus bark.

    PubMed

    Sarin, Vikrant; Pant, K K

    2006-01-01

    Several low cost biomaterials such as baggase, charred rice husk, activated charcoal and eucalyptus bark (EB) were tested for removal of chromium. All the experiments were carried out in batch process with laboratory prepared samples and wastewater obtained from metal finishing section of auto ancillary unit. The adsorbent, which had highest chromium(VI) removal was EB. Influences of chromium concentration, pH, contact time on removal of chromium from effluent was investigated. The adsorption data were fitted well by Freundlich isotherm. The kinetic data were analyzed by using a first order Lagergren kinetic. The Gibbs free energy was obtained for each system and was found to be -1.879 kJ mol(-1) for Cr(VI) and -3.885 kJ mol(-1) for Cr(III) for removal from industrial effluent. The negative value of deltaG0 indicates the feasibility and spontaneous nature of adsorption. The maximum removal of Cr(VI) was observed at pH 2. Adsorption capacity was found to be 45 mg/g of adsorbent, at Cr(VI) concentration in the effluent being 250 mg/l. A waste water sample containing Cr(VI), Cr(III), Mg, and Ca obtained from industrial unit showed satisfactory removal of chromium. The results indicate that eucalyptus bark can be used for the removal of chromium.

  9. Method for fabricating cermets of alumina-chromium systems

    DOEpatents

    Morgan, Chester S.

    1983-01-01

    Cermet insulators resistant to thermal and mechanical shock are prepared from alumina-chromium systems by providing an Al.sub.2 O.sub.3 material of about 0.5 to 7.0 micron size with a solid-hydrocarbon overcoating by slurring an effective amount of said solid hydrocarbon in a solvent mixture containing said Al.sub.2 O.sub.3 and thereafter evaporating said solvent, contacting said coated Al.sub.2 O.sub.3 with a solution of chromium precursor compound, heating the resulting mixture in a reducing environment to a temperature above the decomposition temperature of said chromium precursor compound but less than the melting temperature of the Al.sub.2 O.sub.3 or chromium for sufficient duration to yield a particulate compound having chromium essentially dispersed throughout the Al.sub.2 O.sub.3, and then densifying said particulate to provide said cermet characterized by a theoretical density in excess of 96% and having 0.1 to 10.0 vol.% elemental chromium metal present therein as a dispersed phase at the boundaries of the Al.sub.2 O.sub.3 material. Cermet components prepared thereby are useful in high temperature equipment, advanced heat engines, and nuclear-related equipment applications where electrical or thermal insulators are required.

  10. Evaluating trivalent chromium toxicity on wild terrestrial and wetland plants.

    PubMed

    Lukina, A O; Boutin, C; Rowland, O; Carpenter, D J

    2016-11-01

    Elevated chromium levels in soil from mining can impact the environment, including plants. Mining of chromium is concentrated in South Africa, several Asian countries, and potentially in Northern Ontario, Canada, raising concerns since chromium toxicity to wild plants is poorly understood. In the first experiment, concentration-response tests were conducted to evaluate effects of chromium on terrestrial and wetland plants. Following established guidelines using artificial soil, seeds of 32 species were exposed to chromium (Cr(3+)) at concentrations simulating contamination (0-1000 mg kg(-1)). This study found that low levels of chromium (250 mg kg(-1)) adversely affected the germination of 22% of species (33% of all families), while higher levels (500 and 1000 mg kg(-1)) affected 69% and 94% of species, respectively, from 89% of the families. Secondly, effects on seedbanks were studied using soil collected in Northern Ontario and exposed to Cr(3+) at equivalent concentrations (0-1000 mg kg(-1)). Effects were less severe in the seedbank study with significant differences only observed at 1000 mg kg(-1). Seeds exposed to Cr(3+) during stratification were greatly affected. Seed size was a contributing factor as was possibly the seed coat barrier. This study represents an initial step in understanding Cr(3+) toxicity on wild plants and could form the basis for future risk assessments.

  11. The chemistry of chromium and some resulting analytical problems.

    PubMed Central

    Shupack, S I

    1991-01-01

    Chromium, named for its many-colored compounds, exists in the oxidation states of -2 to +6 inclusively. The compounds exhibit a wide range of geometries including square planar, tetrahedral, octahedral, and various distorted geometries. Chromium is found in nature principally as the chromite ore FeCr2O4 in which chromium is in the +3 state. The existence of a particular oxidation state is dependent on many factors including pH, redox potentials, and kinetics. Thermodynamically, +3 and +2 are the most stable states, while the +3 and +6 oxidation states are the most common ones found in aqueous solution. Kinetically, chromium +3 is substitutionally inert: for water exchange k(sec-1) = 2.5 x 10(-6), due to the presence of the half-filled d(t2g)3.4A2g state. On the other hand, protonation/deprotonation is quite rapid. Polymerization is very slow but is promoted at higher pHs; acid cleavage of the protonated oligomers is also quite slow. Chromium +6 as the chromate ion is strongly oxidizing at low pHs and less so in basic solution. The chromate ion does form some polyacids and polyanions. These factors must be considered in analyzing samples for total chromium and for the amounts of each oxidation state. Images FIGURE 1. PMID:1935853

  12. Environmental monitoring of chromium in air, soil, and water.

    PubMed

    Vitale, R J; Mussoline, G R; Rinehimer, K A

    1997-08-01

    Historical uses of chromium have resulted in its widespread release into the environment. In recent years, a significant amount of research has evaluated the impact of chromium on human health and the environment. Additionally, numerous analytical methods have been developed to identify and quantitate chromium in environmental media in response to various state and federal mandates such as CERCLA, RCRA, CWA, CAA, and SWDA. Due to the significant toxicity differences between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium, it is essential that chromium be quantified in these two distinct valence states to assess the potential risks to exposure to each in environmental media. Speciation is equally important because of their marked differences in environmental behavior. As the knowledge of risks associated with each valence state has grown and regulatory requirements have evolved, methods to accurately quantitate these species at ever-decreasing concentrations within environmental media have also evolved. This paper addresses the challenges of chromium species quantitation and some of the most relevant current methods used for environmental monitoring, including ASTM Method D5281 for air, SW-846 Methods 3060A, 7196A and 7199 for soils, sediments, and waste, and U.S. EPA Method 218.6 for water.

  13. Chromium Exposure and Hygienic Behaviors in Printing Workers in Southern Thailand

    PubMed Central

    Decharat, Somsiri

    2015-01-01

    Objectives. The main objective of this study was to assess the chromium exposure levels in printing workers. The study evaluated the airborne, serum, and urinary chromium levels and determines any correlation between level of chromium in specimen and airborne chromium levels. Material and Methods. A cross-sectional study was conducted with 75 exposed and 75 matched nonexposed subjects. Air breathing zone was measured by furnace atomic absorption spectrophotometer. Serum and urine samples were collected to determine chromium levels by graphite furnaces atomic absorption spectrometer chromium analyzer. Results and Discussion. The printing workers' urinary chromium levels (6.86 ± 1.93 μg/g creatinine) and serum chromium levels (1.24 ± 1.13 μg/L) were significantly higher than the control group (p < 0.001 and p < 0.001). Work position, duration of work, personal protective equipment (PPE), and personal hygiene were significantly associated with urinary chromium level and serum chromium levels (p < 0.001 and p < 0.001). This study found a correlation between airborne chromium levels and urinary chromium levels (r = 0.247, p = 0.032). A multiple regression model was constructed. Significant predictors of urinary and serum chromium levels were shown in this study. Conclusion. Improvements in working conditions, occupational health training, and PPE use are recommended to reduce chromium exposure. PMID:26448746

  14. Chromium released from leather – I: exposure conditions that govern the release of chromium(III) and chromium(VI)

    PubMed Central

    Hedberg, Yolanda S; Lidén, Carola; Odnevall Wallinder, Inger

    2015-01-01

    Background Approximately 1–3% of the adult population in Europe is allergic to chromium (Cr). A new restriction in REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) based on the ISO 17075 standard has recently been adopted in the EU to limit Cr(VI) in consumer and occupational leather products. Objectives The aim of this study was to critically assess key experimental parameters in this standard on the release of Cr(III) and Cr(VI) and their relevance for skin exposure. Material and methods Four differently tanned, unfinished, leather samples were systematically investigated for their release of Cr(III) and Cr(VI) in relation to surface area, key exposure parameters, temperature, ultraviolet irradiation, and time. Results Although the total release of Cr was largely unaffected by all investigated parameters, except exposure duration and temperature, the Cr oxidation state was highly dynamic, with reduced amounts of released Cr(VI) with time, owing to the simultaneous release of reducing agents from the leather. Significantly more Cr(III) than Cr(VI) was released from the Cr-tanned leather for all conditions tested, and it continued to be released in artificial sweat up to at least 1 week of exposure. Conclusions Several parameters were identified that influenced the outcome of the ISO 17075 test. PMID:25653094

  15. Simultaneous Electrodialytic Preconcentration and Speciation of Chromium(III) and Chromium(VI).

    PubMed

    Ohira, Shin-Ichi; Nakamura, Koretaka; Shelor, C Phillip; Dasgupta, Purnendu K; Toda, Kei

    2015-11-17

    Large amounts of chromium (Cr) compounds are used for manufacturing of various products and various chemical processes. Some inevitably find their way into the environment. Environmental Cr is dominantly inorganic and is either in the cationic +3 oxidation state or in the anionic oxochromium +6 oxidation state. The two differ dramatically in their implications; Cr(III) is essential to human nutrition and even sold as a supplement, while Cr(VI) is a potent carcinogen. Drinking water standards for chromium may be based on total Cr or Cr(VI) only. Thus, Cr speciation analysis is very important. Despite their high sensitivity, atomic spectrometric techniques or induction coupled plasma-mass spectrometry (ICP-MS) cannot directly differentiate the oxidation states. We present here a new electrodialytic separation concept. Sample analyte ions are quantitatively transferred via appropriately ionically functionalized dialysis membranes into individual receptors that are introduced into the ICP-MS. There was no significant conversion of Cr(VI) to Cr(III) or vice versa during the very short (6 s) separation process. Effects of salinity (up to ∼20 mM NaCl) can be eliminated with proper membrane functionalization and receptor optimization. With the ICP-MS detector we used, the limits of detection for either form of Cr was 0.1 μg/L without preconcentration. Up to 10-fold preconcentration was readily possible by increasing the donor solution flow rate relative to the acceptor solution flow rates. The proposed approach permits simultaneous matrix isolation, preconcentration, and chromium speciation.

  16. Enhancement of oxidative vaporization of chromium (III) oxide and chromium by oxygen atoms

    NASA Technical Reports Server (NTRS)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1974-01-01

    Rates of oxidative vaporization of Cr2O3 were found to be markedly enhanced in the presence of O atoms. Investigations were conducted over the temperature range 470 to 1520 K. For Cr2O3 the enhancement was about 10 to the 9th power at 820 K in oxygen containing 2.5 percent atoms. Rapid oxidative vaporization of bare chromium was observed below 1070 K, the rate being about one-half that of Cr2O3. Results are interpreted in terms of thermochemical analysis.

  17. The removal of hexavalent chromium from water by ferrous sulfate

    SciTech Connect

    Lin, C.J.J.; Vesilind, P.A.

    1995-12-31

    The redox reaction of hexavalent chromium and ferrous sulfate is investigated in his study. Hexavalent chromium, a highly toxic and mobile anion, could exist in raw water used as a public water supply due to the industrial chromium contamination of natural water or due to natural oxidation of trivalent chromium. Ferrous sulfate is one of the widely used coagulants in water treatment plants and has good reducing ability. Because of its reducing capacity, ferrous sulfate can be applied to remove hexavalent chromium from water. The required contact time to reach equilibrium, the effectiveness of Cr(VI) reduction at different initial pH, and the required ferrous sulfate dosage for complete reduction are investigated. The redox reaction can be completed within 10 minutes, allowing 30 mg/L of hexavalent chromium to react with stoichiometric dosage of ferrous sulfate in deionized water, regardless of the initial pH. The pH of the solution is depressed during the progress of the reaction due to the hydrolysis of the produced Fe(III) and Cr(III) ions from the reaction. Dissolved oxygen in water is found to interfere with the redox reaction by consuming ferrous ions when the initial pH of solutions is high. In deionized water, complete Cr(VI) reduction can be achieved by applying excess ferrous sulfate under the condition of this study. It is also achievable when the raw water from Durham Water Treatment Plant is used as the reaction medium, without additional dosage of ferrous sulfate. Based on the results, simultaneous removal of hexavalent chromium in water treatment by applying ferrous sulfate as the coagulant is theoretically feasible.

  18. A Rare Terminal Dinitrogen Complex of Chromium

    SciTech Connect

    Mock, Michael T.; Chen, Shentan; Rousseau, Roger J.; O'Hagan, Molly J.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.; Bullock, R. Morris

    2011-10-12

    The reduction of dinitrogen to ammonia from N2 and H2 is currently carried out by the Haber-Bosch process, an energy intensive process that requires high pressures and high temperatures and accounts for the production of millions of tons of ammonia per year. The development of a catalytic, energy-efficient process for N2 reduction is of great interest and remains a formidable challenge. In this communication, we are reporting the preparation, characterization and computational electronic structure analysis of a rare 'Chatt-type' ((P-P)2M(N2)2, P-P = diphosphine ligand) complex of chromium, cis-[Cr(N2)2(PPh2NBn2)2] and its reactivity with CO. This complex is supported by the diphosphine ligand PPh2NBn2, containing non-coordinating pendant amine bases, to serve as proton relays. Future studies for this complex are aimed at answering fundamental questions regarding the role of proton relays in the second coordination sphere in their ability to facilitate proton movement from an external acid to metal-bound dinitrogen ligands in the challenging multi-proton/electron reduction of N2 to ammonia.

  19. Uptake, Distribution and Speciation of Chromium

    SciTech Connect

    Bluskov,S.; Arocena, J.; Omotoso, O.; Young, J.

    2005-01-01

    Brassica juncea (Indian mustard) has been widely used in phytoremediation because of its capacity to accumulate high levels of chromium (Cr) and other metals. The present study was conducted to investigate mechanism(s) involved in Cr binding and sequestration by B. juncea. The plants were grown under greenhouse conditions in field-moist or air-dried soils, amended with 100 mg kg -1 of Cr (III or VI). The plant concentrated Cr mainly in the roots. B. juncea removed an average of 48 and 58 {mu}g Cr per plant from Cr (III) and Cr (VI)-treated soils, respectively. The uptake of Cr was not affected by the moisture status of the soils. X-ray absorption near-edge spectroscopy measurements showed only Cr (III) bound predominantly to formate and acetate ligands, in the bulk and rhizosphere soils, respectively. In the plant tissues, Cr (III) was detected, primarily as acetate in the roots and oxalate in the leaves. X-ray microprobe showed the sites of Cr localization, and probably sequestration, in epidermal and cortical cells in the roots and epidermal and spongy mesophyll cells in the leaves. These findings demonstrate the ability of B. juncea to detoxify more toxic Cr (VI), thereby making this plant a potential candidate for phytostabilization.

  20. Hexavalent chromium-resistant bacteria isolated from river sediments.

    PubMed Central

    Luli, G W; Talnagi, J W; Strohl, W R; Pfister, R M

    1983-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen and mutagen; however, the actual mechanisms of Cr toxicity are unknown. Two approaches were used to isolate Cr(VI)-resistant bacteria from metal-contaminated river sediments. Diluted sediments were plated directly onto a peptone-yeast extract (PYE) medium containing 0 to 100 micrograms of Cr(VI) ml-1. Approximately 8.4 x 10(5) CFU g-1 were recovered on 0 microgram of Cr(VI) ml-1, whereas 4.0 x 10(2) CFU g-1 were recovered on PYE plus 100 micrograms of Cr(VI) ml-1. Alternatively, continuous culture enrichment techniques were employed using PYE and 100 micrograms Cr(VI) ml-1 input at dilution rates of 0.02 and 0.10 h-1. After six residence periods, 10(9) CFU were recovered on PYE agar containing 0 microgram of Cr(VI) ml-1 and 10(7) CFU on PYE agar plus 100 micrograms of Cr(VI) ml-1. Of 89 isolates obtained by direct plating onto PYE, 47% were resistant to 100 micrograms of Cr(VI) ml-1, and 29% were resistant to 250 micrograms of Cr(VI) ml-1. When the same isolates were plated onto PYE containing Cr(III), 88% were resistant to 100 micrograms ml-1 but only 2% were resistant to 250 micrograms ml-1. Cr, Co, Sb, and Zn were found in significantly higher concentrations at an industry-related contaminated site than at a site 11 km downstream. Total Cr in the sediments at the contaminated site averaged 586 micrograms (dry weight) g-1, and the downstream site averaged 71 micrograms (dry weight) g-1. The Cr recovered from acid-digested Ottawa River sediment samples was predominantly hexavalent. Five acid digestion procedures followed by atomic absorption spectroscopy were compared and found to be 30 to 70% efficient for recovery of Cr relative to neutron activation analysis. A population of aerobic, heterotrophic bacteria was recovered from sediments containing elevated levels of Cr.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6639032

  1. Increase of chromium yield by slag reduction during production of chromium steels

    NASA Astrophysics Data System (ADS)

    Bažan, J.; Socha, L.; Kurka, V.; Jonšta, P.; Sušovský, M.

    2017-02-01

    The paper is focused on the evaluation of the course of Cr2O3 reduction from slag to alloyed steel under laboratory conditions. The experiments were aimed at the evaluation of increase in the chromium content in the melt together with the studying the behaviour of Cr2O3 and the mechanism of reduction by means of three reducing agents. Anthracite, ferrosilicon and mixtures of anthracite and ferrosilicon belong among the selected reducing agents. The experimental melts were focused on the proposal of a theoretical calculation of the consumption of selected reducing agents, study of reduction under laboratory conditions at application of alloyed steel with content of chromium of 12.16 wt. %, temperatures of 1600 °C and 1650 °C, together with the change of amount of reducing agents and reduction time. The results indicated in the paper constitute basic information on the possibilities of Cr2O3 reduction from slag; they will be used for verification of results in the pilot plant and operation experiments which will simulate operating conditions in the electric arc furnace.

  2. Spectroscopic study for a chromium-adsorbed montmorillonite

    NASA Astrophysics Data System (ADS)

    Nurtay, Maidina ·; Tuersun, Maierdan ·; Cai, Yuanfeng; Açıkgöz, Muhammed; Wang, Hongtao; Pan, Yuguan; Zhang, Xiaoke; Ma, Xiaomei

    2017-02-01

    Samples of purified montmorillonite with trace amounts of quartz were subjected to different concentrations of chromium sulphate solutions for one week to allow cation exchange. The chromium-bearing montmorillonites were verified and tested using powder X-ray diffractometry (XRD), X-ray fluorescence spectrometry, electron spin resonance (ESR) spectrometry and Fourier transformation infrared (FTIR) spectroscopy to explore the occupation sites of the chromium. The ESR spectra recorded before and after the chromium exchange show clear differences: a strong and broad resonance with two shoulders at the lower magnetic field side was present to start, and its intensity as well as that of the ferric iron resonance, increased with the concentration of added chromium. The signals introduced by the chromium, for example at g = 1.975 and 2.510 etc., suggested that the chromium had several occupational sites. The ESR peak with g = 2.510 in the second derivative spectrum suggested that Cr3+ was weakly bounded to TOT with the form of [Cr(H2O)3]3+ in hexagonal cavities. This was verified by comparing the FTIR spectra of the pure and modified montmorillonite. The main resonance centred at g = 1.975 indicated that the majority of Cr3+ occupied the interlayer region as [Cr(H2O)6]3+. The substitution of Ca2 + by Cr3+ also greatly affected the vibration of the hydrogens associate to water, ranged from 3500 to 2600 cm-1 in FTIR. Furthermore, the presence of two diffraction lines in the XRD results (specifically those with d-values of 1.5171 and 1.2673 nm) and the calculations of the size of the interlayer space suggested the presence of two types of montmorillonite with different hydration cations in the sample exposed to 0.2 M chromium sulphate. The two diffraction lines were assigned to [Cr(H2O)6]3+ and [Cr(H2O)3O3]3+, respectively. This also suggested that the species of hydration cation was constrained by the concentration of the chromium solution.

  3. Co-removal of hexavalent chromium during copper precipitation.

    PubMed

    Sun, J; Huang, J C

    2002-01-01

    In our recent study using the nucleated precipitation technology to treat plating wastewater, it was found that about one half of hexavalent chromium was co-removed with copper, nickel and zinc. Since hexavalent chromium could not react with either hydroxide or carbonate to from precipitates, this study was undertaken to evaluate the mechanism(s) involved in the chromium co-removal. Batch tests were conducted with synthetic solutions containing either only copper or both copper and hexavalent chromium. Metal precipitation was induced by adding Na2CO3 to different pH, and the quantitative removal of copper and chromium was determined. Besides, the [Cr]/[Cu] molar ratio of produced precipitates were also assessed in conjunction with the EDAX analysis to determine their compositions. Experimental results indicate that for pure copper solution, precipitation begins at pH 6.0, and completes at pH 7.0. The chemical forms of the precipitates are copper carbonates [CuCO3 x Cu(OH)2 and CuCO3 x 2Cu(OH)2]. On the other hand, in a bi-metal solution of copper plus chromium, precipitation of copper begins at about pH 5.0, and copper precipitation is always accompanied by some chromium removal. From the removal stoichiometry of the two metals, it is found that at low pH, the co-removal is a result of "co-precipitation" which results in the formation of CuCrO4 crystallites. Once such crystallites are formed, they provide a heterogeneous environment which enhances an early formation of copper carbonate at a lower pH (below 5.5). It is further found that once copper carbonate precipitates are produced, the remaining soluble will precipitate in such form, and at this stage further removal of copper is no longer accompanied by additional chromium removal. The test data also reflect that the produced copper carbonates are positively charged, as verified by zeta potential measurement, at pH below 7.5. Thus they are able to adsorb some anionic chromium (existing as chromate) through

  4. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    SciTech Connect

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander; Adamski, Paweł; Moszyński, Dariusz

    2016-09-15

    Four nanocomposites containing mixed phases of Co{sub 3}Mo{sub 3}N and Co{sub 2}Mo{sub 3}N doped with chromium have been prepared. A linear fit is found for relation between Co{sub 2}Mo{sub 3}N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2–300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping. - Highlights: • A new chromium doped mixed Co-Mn-N nanocomposites were synthesized. • Surface ferromagnetism was detected in a wide temperature range. • Core-shell model was applied to explain nanocomposites magnetism.

  5. [Occupational exposure to hexavalent chromium during aircraft painting].

    PubMed

    Gherardi, M; Gatto, M P; Gordiani, A; Paci, E; Proietto, A

    2007-01-01

    Hygienists are interested in hexavalent chromium due to its genotoxic and carcinogenic effect on humans. The use of products containing hexavalent chromium is decreasing in many industrial fields because of the substitution with less-toxic compounds. In the aeronautical industry, however, the chromate are added to primer paint as a corrosion inhibitor of aircrafts surfaces: so hexavalent chromium compounds are available in many primers with a composition ranging from 10% to 13%. The application of these primers by using electrostatic guns potentially exposes painting and coating workers at high concentrations of aerosols containing Cr(VI). The aim of the present study is the evaluation of professional exposure to hexavalent chromium during aircraft painting, by adopting both environmental personal sampling and biological monitoring. To valuate workers exposure levels the personal measurements results have been compared with the exposure limit values (TLV-TWA) and the urinary chromium contents with the biological exposure indices (IBE). Moreover the strategy of coupling environmental sampling with biological monitoring seems to be a useful instrument to measure the validity of the individual protection devices.

  6. Chromium recovery from tannery sludge with saponin and oxidative remediation.

    PubMed

    Kiliç, Eylem; Font, Joaquim; Puig, Rita; Colak, Selime; Celik, Deniz

    2011-01-15

    Two new methods for treatment of tannery sludge were studied to achieve cost-effective and environmentally acceptable remediation solutions for high chromium containing tannery sludge. Quillaja bark saponin, a plant derived biosurfactant, was applied to dewatered tannery sludge for chromium recovery and a comparative assessment with H(2)O(2) oxidative treatment method is presented. Tannery sludge samples were treated on a laboratory scale with saponin in the pH range 2-3. The effects of various factors like time, concentration of saponin, pH, and temperature on the extraction of chromium were studied. The treatment with saponin extracted 24% of Cr from tannery sludge at a pH around2, performing multiple wash of 6h, at 33 °C. On the other hand, the H(2)O(2) treatment, which include Cr(III) oxidation to Cr(VI) and extraction with sulfuric acid solution at pH 2, enabled to extract 70% of chromium within less than 4h at room temperature (21 °C). The results indicate that the extraction efficiency of saponin was strongly dependent on the organic matter content of the sample, which affects chromium mobility by its high adsorption capacity. On the other hand hydrogen peroxide treatment is effective and the duration of the process is short and requires cheap chemicals and moderate conditions.

  7. Low-chromium reduced-activation ferritic steels for fusion

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.; Kenik, E.A.

    1996-04-01

    Development of reduced-activation ferritic steels has concentrated on high-chromium (8-10 wt% Cr) steels. However, there are advantages for a low-chromium steel, and initial ORNL studies on reduced-activation steels were on compositions with 2.25 to 12% Cr. Those studies showed an Fe-2.25Cr-2W-0.25V-0.1C (2 1/4Cr-2WV) steel to have the highest strenglth of the steels studied. Although this steel had the best strength, Charpy impact properties were inferior to those of an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) and an Fe-2.25Cr-2W-0.1C (2 1/4Cr-2W) steel. Therefore, further development of the low-chromium Cr-W steels was required. These results indicate that it is possible to develop low-chromium reduced-activation ferritic steels that have tensile and impact properties as good or better than those of high-chromium (7-9% Cr) steels. Further improvement of properties should be possible by optimizing the composition.

  8. Thermodynamics of chromium in UO2 fuel: A solubility model

    NASA Astrophysics Data System (ADS)

    Riglet-Martial, Ch.; Martin, Ph.; Testemale, D.; Sabathier-Devals, C.; Carlot, G.; Matheron, P.; Iltis, X.; Pasquet, U.; Valot, C.; Delafoy, C.; Largenton, R.

    2014-04-01

    The solubility and speciation of chromium in doped uranium oxide are measured in carefully controlled temperature and oxygen potential conditions using electron probe microanalysis (EPMA) and scanning electron spectroscopy (SEM). The examination of the samples by X-ray Absorption Spectroscopy (XAS) provides evidence that (i) chromium is soluble in the UO2 matrix under the +3 oxidation state only regardless of the sintering conditions which is in accordance with a soluble species of type CrO3/2 and (ii) soluble chromium exhibits octahedral symmetry with 6 atoms of oxygen forming CrO6 patterns in the UO2 structure. In consistency with all available experimental information including previously published data, the solubility of chromium in UO2 corresponding to each two-phase field with either Cr, CrO and Cr2O3 may be described in the ranges 1500 °C < T < 2000 °C and -460 < μO2 < -360 kJ/mol using the standard thermodynamic equations governing solubility equilibria. The characteristic parameters of the solubility laws in UO2 for the three chromium phases are derived.

  9. Enhancement of chromium uptake in tanning using oxazolidine.

    PubMed

    Sundarapandiyan, S; Brutto, Patrick E; Siddhartha, G; Ramesh, R; Ramanaiah, B; Saravanan, P; Mandal, A B

    2011-06-15

    Monocyclic and bicyclic oxazolidines were offered at three different junctures of chrome tanning process viz. prior to BCS offer, along with BCS and after basification. It was found that oxazolidine when offered after basification brought about better chromium uptake and reduction of chromium load in the wastewater. Offer of oxazolidine was also varied. Increase in offer of oxazolidine from 0.25% to 1% was found to enhance the chromium uptake and decrease the chromium load in wastewater. But the increase in uptake was not proportionate to the increase in oxazolidine offer more than 0.75%. Offer of 1% Zoldine ZA 78 (monocyclic oxazolidine) and Zoldine ZE (bicyclic oxazolidine) after basification brought about 63.4% and 73.1% enhancement in chrome content in leather compared to control where oxazolidine was not offered. The tone of the wetblue was found to be altered moderately. However this did not call for any process adjustments in wet-finishing. The oxazolidine treated leathers were found to be immensely fuller and tighter. It was found experimentally that offer of 1% of oxazolidine facilitated reduction in the offer of syntans administered for filling and grain tightening by around 46%. Oxazolidine could bring about significant reduction in cost of chemicals apart from resulting environmental benefits due to enhancement of chromium uptake during tanning.

  10. Microbial exudate promoted dissolution and transformation of chromium containing minerals

    NASA Astrophysics Data System (ADS)

    Saad, E. M.; Sun, J.; Tang, Y.

    2015-12-01

    Because of its utility in many industrial processes, chromium has become the second most common metal contaminant in the United States. The two most common oxidation states of chromium in nature are Cr(III), which is highly immobile, and Cr(VI), which is highly mobile and toxic. In both natural and engineered environments, the most common remediation of Cr(VI) is through reduction, which results in chromium sequestration in the low solubility mixed Cr(III)-Fe(III) (oxy)hydroxide phases. Consequently, the stability of these minerals must be examined to assess the fate of chromium in the subsurface. We examined the dissolution of mixed Cr(III)-Fe(III) (oxy)hydroxides in the presence of common microbial exudates, including the siderophore desferrioxamine B (DFOB; a common organic ligand secreted by most microbes with high affinity for ferric iron and other trivalent metal ions) and oxalate (a common organic acid produced by microbes). The solids exhibited incongruent dissolution with preferential leaching of Fe from the solid phase. Over time, this leads to a more Cr rich mineral, which is known to be more soluble than the corresponding mixed mineral phase. We are currently investigating the structure of the reacted mineral phases and soluble Cr(III) species, as well as the potential oxidation and remobilization of the soluble Cr species. Results from this study will provide insights regarding the long term transport and fate of chromium in the natural environment in the presence of microbial activities.

  11. A possible role for chromium(III) in genotoxicity

    SciTech Connect

    Snow, E.T. )

    1991-05-01

    Chromium is found in the environment in two major forms: reduced Cr{sup III} and Cr{sup VI}, or chromate. Chromate, the most biologically active species, is readily taken up by living cells and reduced intracellularly, via reactive intermediates, to stable Cr{sup III} species. Cr{sup III}, the most abundant form of chromium in the environment, does not readily cross cell membranes and is relatively inactive in vivo. However, intracellular Cr{sup III} can react slowly with both nucleic acids and proteins and can be genotoxic. The authors have investigated the genotoxicity of Cr{sup III} in vitro using a DNA replication assay and in vivo by CaCl{sub 2}-mediated transfection of chromium-treated DNA into Escherichia coli. These results suggest that Cr{sup III} alters the interaction between the DNA template and the polymerase such that the binding strength of the DNA polymerase is increased and the fidelity of DNA replication is decreased. These interactions may contribute to the mutagenicity of chromium ions in vivo and suggest that Cr{sup III} can contribute to chromium-mediated carcinogenesis.

  12. Impact of pyrolysis process on the chromium behavior of COPR.

    PubMed

    Zhang, Dalei; He, Shengbing; Dai, Luwei; Xie, Yaning; Wu, Deyi; Bu, Guanhua; Peng, Kangjin; Kong, Hainan

    2009-12-30

    The effect of pyrolysis process with sewage sludge on the chromium behavior of chromite ore processing residue (COPR) was examined in this study. The behavior of chromium was characterized in term of chromium oxidation test, pH-static leaching tests, column leaching test and sequential extraction test. As a sequence of pyrolysis process, the Cr(VI) in COPR was effectively reduced from 5057 mg kg(-1) for untreated COPR to 8.6 mg kg(-1) for treated COPR at temperature over 600 degrees C, which is far below the New Jersey Department of Environmental Protection regulatory limit of 240 mg kg(-1). As a result, the amount of exchangeable and carbonate-bound Cr fractions, the most mobile for the environment, were largely reduced. At the same time, the amount of the other three Cr fractions which are much less mobile become augmented. pH static test showed that the chromium in the treated COPR at pyrolysis temperature above 400 degrees C was quite stable at pH>7. Column study also indicated that only negligible amount of chromium of the treated COPR at above 600 degrees C can be released by the acid rain.

  13. Chromium accumulation in three species of central Florida centrarchids

    SciTech Connect

    Campbell, K.R. |

    1995-02-01

    Stormwater ponds are required in Central Florida when land is developed to treat the resulting stormwater. The St. Johns River Water Management District, the agency that regulates stormwater discharges in Central Florida, frequently approves plans that create habitat for fish and wildlife by planting desirable wetland and aquatic vegetation in the littoral zones of stormwater ponds to compensate for the loss of wetlands. The various species of fish that inhabit stormwater ponds serve as a food source to wildlife, especially wading birds. The objective of this study was to determine if fish that live in stormwater treatment ponds in Orlando, Florida contained significant concentrations of chromium. In order to determine if there were differences in chromium concentrations in fish with different foraging strategies, three species of sunfish (Centrarchidae) with substantially different foraging strategies were selected for this study: largemouth bass (Micropterus salmoides), a predator; redear sunfish (Lepomis microlophus), a bottom feeder; and bluegill sunfish (Lepomis macrochirus), an omnivore. Many researchers have shown that large quantities of chromium are found in urban runoff. Chromium sources are largely associates with the operation of motor vehicles. Several investigators have determined that chromium from urban runoff concentrates in the sediment of stormwater ponds. Sediments represent the most concentrated physical pool of metals in aquatic environments, and they are ingested by many types of aquatic organisms. Most fish are capable of accumulating heavy metals from their diet and from water through their gills. 17 refs., 1 fig., 3 tabs.

  14. CHROMIUM ELECTROANALYSIS AT SCREEN PRINTED ELECTRODE MODIFIED BY THIN FILMS OF NICKEL

    EPA Science Inventory

    A rapid and potentially cost-effective electrochemical method is reported for analysis of chromium (VI) and Chromium(III) using a nickel modified screen printed carbon ink electrode. Electrochemical characteristics of nickel modified electrode as well voltammetric behavior f...

  15. Effective bioleaching of chromium in tannery sludge with an enriched sulfur-oxidizing bacterial community.

    PubMed

    Zeng, Jing; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Sun, Zhao-Yong; Kida, Kenji

    2016-10-01

    In this study, a sulfur-oxidizing community was enriched from activated sludge generated in tannery wastewater treatment plants. Bioleaching of tannery sludge containing 0.9-1.2% chromium was investigated to evaluate the effectiveness of the enriched community, the effect of chromium binding forms on bioleaching efficiency, and the dominant microbes contributing to chromium bioleaching. Sludge samples inoculated with the enriched community presented 79.9-96.8% of chromium leaching efficiencies, much higher than those without the enriched community. High bioleaching efficiencies of over 95% were achieved for chromium in reducible fraction, while 60.9-97.9% were observed for chromium in oxidizable and residual fractions. Acidithiobacillus thiooxidans, the predominant bacteria in the enriched community, played an important role in bioleaching, whereas some indigenous heterotrophic species in sludge might have had a supporting role. The results indicated that A. thiooxidans-dominant enriched microbial community had high chromium bioleaching efficiency, and chromium binding forms affected the bioleaching performance.

  16. Process for improving moisture resistance of epoxy resins by addition of chromium ions

    NASA Technical Reports Server (NTRS)

    St.clair, A. K.; Stoakley, D. M.; St.clair, T. L.; Singh, J. J. (Inventor)

    1985-01-01

    A process for improving the moisture resistance properties of epoxidized TGMDA and DGEBA resin system by chemically incorporating chromium ions is described. The addition of chromium ions is believed to prevent the absorption of water molecules.

  17. Thiocyanato Chromium (III) Complexes: Separation by Paper Electrophoresis and Estimate of Stability Constants

    ERIC Educational Resources Information Center

    Larsen, Erik; Eriksen, J.

    1975-01-01

    Describes an experiment wherein the student can demonstrate the existence of all the thiocyanato chromium complexes, estimate the stepwise formation constants, demonstrate the robustness of chromium III complexes, and show the principles of paper electrophoresis. (GS)

  18. 75 FR 18041 - Defense Federal Acquisition Regulation Supplement; Minimizing Use of Hexavalent Chromium (DFARS...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-08

    ... requirements for minimizing the use of hexavalent chromium in defense weapon systems, subsystems, components... INFORMATION: A. Background Hexavalent chromium is a significant chemical in numerous DoD weapon systems...

  19. FORMATION AND DESTRUCTION OF HEXAVALENT CHROMIUM IN A LABORATORY SWIRL FLAME INCINERATOR

    EPA Science Inventory

    The partitioning of chromium (Cr) in combustion systems was investigated theoretically and experimentally. Theoretical predictions were based on chemical equilibrium and suggested that hexavalent chromium [Cr(VI)] was favored by the presence of chlorine (Cl) and diminished by the...

  20. Immobilization of chromium in cement matrices

    SciTech Connect

    Kindness, A.; Macias, A.; Glasser, F.P. . Dept. of Chemistry)

    1994-01-01

    Portland cement and blended cements containing blast furnace slag afford both physical and chemical immobilization of chromium. To separate physical and chemical effects, the pore fluid contained in set, hydrated cements has been expressed and analyzed. In Portland cement spiked with 5,000 ppm Cr(III), pore fluid levels are 0.1--1 ppm, whereas in well-cured slag blends, they decrease to <0.01 ppm. Both cement types give chemical immobilization, but slag cements give the better performance. Slag-containing cements are the most effective at removing Cr(VI) from the pore fluid, probably by reducing Cr(VI) to Cr(III). Electron microscopy coupled with energy dispersive X-ray analysis shows that Cr(III) can be substituted for Al in most of the calcium aluminated hydrate phases. In synthetic preparations, substitution is complete resulting in Ca-Cr phases that are isostructural to calcium aluminate phases. Three Cr analogues of calcium aluminates were synthesized: Ca[sub 2]Cr(OH)[sub 7] [center dot] 3H[sub 2]O, Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 6H[sub 2]O and Ca[sub 2]Cr[sub 2]O[sub 5] [center dot] 8H[sub 2]O, as well as solid solutions, e.g., Cr substituted hydrogarnet 3CaO [center dot] (Al[sub 2]O[sub 3]/Cr[sub 2]O[sub 3]) [center dot] 6H[sub 2]O. There is no real evidence that Cr is taken up by C-S-H gel.

  1. Effects of chromium-loaded chitosan nanoparticles on growth, blood metabolites, immune traits and tissue chromium in finishing pigs.

    PubMed

    Wang, Min-Qi; Wang, Chao; Li, Hui; Du, Yong-Jie; Tao, Wen-Jing; Ye, Shan-Shan; He, Yu-Dan

    2012-11-01

    Effects of chromium-loaded chitosan nanoparticles (Cr-CNP) on growth performance, blood metabolites, immune traits, and tissue chromium in finishing pigs were investigated. A total of 160 crossbred barrows (66.06 ± 1.01 kg initial weight) were randomly divided into four groups, each group with four pens, ten pigs per pen. Pigs were fed on the same basal diet supplemented with 0 (the control), 100, 200, and 400 μg/kg Cr from Cr-CNP. All pigs were given free access to feed and water. Eight pigs from each treatment were selected to collect blood and tissue samples after 35 days on trial for analysis of blood metabolites and immune traits and tissue chromium. The results of feeding trial showed that there were no significant difference in growth performance between control and Cr-CNP-treated groups. The supplementation of Cr-CNP decreased serum glucose (P < 0.001) in a linear and quadratic manner. Serum immunoglobulins A and M were linearly increased in Cr-CNP-treated groups (P < 0.001), and serum complement 4 in Cr-CNP-treated groups was also linearly increased (P < 0.05). Cr-CNP supplementation linearly increased the chromium content in the blood, longissimus muscle, heart, liver, kidney, and pancreas (P < 0.001). These results suggested that dietary supplementation of Cr as Cr-CNP affects serum glucose, influences immune status, and increases the tissue chromium content of blood, muscle, and selected organs in finishing pigs.

  2. Bioabsorption of chromium from retan chrome liquor by cyanobacteria.

    PubMed

    Pandi, M; Shashirekha, V; Swamy, Mahadeswara

    2009-01-01

    The bioaccumulation of chromium from retan chrome liquor by Spirulina fusiformis was investigated under laboratory as well as field conditions. At the optimal conditions, metal ion uptake increased with initial metal ion concentration up to 300mg/l. The effect on various physico-chemical parameters like total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), chlorides, sulphates, phenols, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) and biochemical studies related to biomass, chlorophyll-a and protein were also carried out. The present study indicates that S. fusiformis is very effective in removal of chromium (93-99%) besides removing other toxicants from retan chrome liquor. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and FTIR studies indicate the interaction/complexation between Cr and alga. The mechanism involved in bioaccumulation of chromium is also discussed. The process when upgraded can be applied for detoxification of tannery effluents.

  3. Extraction of Chromium from Carbon Ferrochromium Residual Wastes

    NASA Astrophysics Data System (ADS)

    Lazarevskiy, P. P.; Gizatulin, R. A.; Romanenko, Yu E.; Valuev, D. V.; Valueva, A. V.; Serikbol, A.

    2015-09-01

    This work reports the problem of processing residual wastes after producing carbon ferrochrome by recycling dust using a hydrometallurgical method with the purpose of extracting the basic component - chromium, The X-ray diffraction analysis results, chemical and granulometric compositions of dust from the carbon ferrochrome production are given, The method for the production of chemical-enrichment concentrate (CEC) by processing ferrous dust is described, with obtaining a middling product - sodium mono-chromate with its further reduction to chromium hydroxide, followed by autoclave leaching, and resulting in the production of chemically enriched chrome concentrate, The plant used for autoclave leaching and filtering is schematically depicted, The smelting process of metallic chromium using the ladle aluminothermic method is described,

  4. Factors affecting the adsorption of chromium (VI) on activated carbon

    SciTech Connect

    Yavuz, R.; Orbak, I.; Karatepe, N.

    2006-09-15

    The aim of this investigation was to determine the adsorption behavior of chromium (VI) on two different activated carbon samples produced from Tuncbilek lignite. The effects of the initial chromium (VI) concentration (250-1000 mg/L), temperature (297-323 K) and pH (2.0-9.5) on adsorption were investigated systematically. The effectiveness of the parameters on chromium adsorption was found to be in the order of pH, the initial Cr(VI) concentration and the temperature. Increasing the pH from 2.0 to 9.5 caused a decrease in adsorption. However, the adsorption was increased by increasing the initial Cr(VI) concentration and temperature. The multilinear mathematical model was also developed to predict the Cr(VI) adsorption on activated carbon samples within the experimental conditions.

  5. Spectroscopic characteristics of chromium-doped mullite glass-ceramics

    SciTech Connect

    Wojtowicz, A.J.; Meng, W.; Lempicki, A.; Beall, G.H.; Hall, D.W.

    1988-06-01

    The chromium (3+) ion has been widely used as an optical activator in solid-state, tunable laser materials. High octahedral field-stabilization energy and resistance against both oxidation and reduction minimize the dependence of chromium (3+) on the solid-state host matrix. However, the high sensitivity of electronic structure on crystal field strength makes the appropriate choice of host the condition for success. Characteristics of chromium-doped mullite ceramics are discussed with reference to possible laser applications. Dominant features are attributed to large and inherent spectroscopic inhomogeneity of mullite. The spectroscopic data are analyzed using a generalized McCumber theory. The peak-stimulated emission cross section is 0.54 x 10 to the -20 sq cm. This together with preliminary single-pass measurements, indicate that gain for mullite is about 2.6 times smaller than gain for alexandrite.

  6. The nature of temper brittleness of high-chromium ferrite

    SciTech Connect

    Sarrak, V.I.; Suvorova, S.O.; Golovin, I.S.; Mishin, V.M.; Kislyuk, I.V.

    1995-03-01

    The reasons for development of {open_quotes}475{degrees}C brittleness{close_quotes} of high-chromium ferritic steels are considered from the standpoint of fracture mechanics. It is shown that the general rise in the curve of temperature-dependent local flow stress has the decisive influence on the position of the ductile-to-brittle transformation temperature and the increase in it as the result of a hold at temperatures of development of brittleness. The established effect is related to the change in the parameters determining dislocation mobility, that is, the activation energy of dislocation movement in high-chromium ferrite and the resistance to microplastic deformation, both caused by processes of separation into layers of high-chromium ferrite and decomposition of the interstitial solid solution.

  7. Electron magnetic resonance investigation of chromium diffusion in yttria powders

    NASA Astrophysics Data System (ADS)

    de Biasi, R. S.; Grillo, M. L. N.

    2010-03-01

    The electron magnetic resonance (EMR) technique was used to investigate the diffusion of chromium in yttria (Y 2O 3) powders. The EMR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323 and 1373 K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be E A=342±5 kJ mol -1. This value is larger than the activation energy for the diffusion of chromium in rutile (TiO 2), periclase (MgO) and cobalt monoxide (CoO) and smaller than the activation energy for the diffusion of chromium in chrysoberyl (BeAl 2O 4).

  8. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  9. Chromium supplementation alters the glucose and lipid metabolism of feedlot cattle during the receiving period

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crossbreed steers (n = 20; 235 ± 4 kg) were fed 53 d during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brand Chromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0 (C...

  10. 75 FR 80457 - Superalloy Degassed Chromium From Japan: Final Results of Sunset Review and Revocation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ... International Trade Administration Superalloy Degassed Chromium From Japan: Final Results of Sunset Review and... the sunset review of the antidumping duty order on superalloy degassed chromium (SDC) ] from Japan... antidumping duty order on SDC from Japan. See Antidumping Duty Order: Superalloy Degassed Chromium from...

  11. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of...

  12. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  13. 48 CFR 252.223-7008 - Prohibition of Hexava-lent Chromium.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Chromium. 252.223-7008 Section 252.223-7008 Federal Acquisition Regulations System DEFENSE ACQUISITION... of Provisions And Clauses 252.223-7008 Prohibition of Hexava-lent Chromium. As prescribed in 223.7306, use the following clause: Prohibition of Hexavalent Chromium (JUN 2013) (a) Definitions. As used...

  14. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of...

  15. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  16. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  17. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  18. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  19. Enhancement of the acute phase response to lipopolysaccharide (LPS) challenge in steers supplemented with chromium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study examined the effect of chromium supplementation on the response of steers to an LPS challenge. Twenty steers received a premix that added 0 (control) or 0.2 mg/kg of chromium (KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) to the total diet on a dry matter basis for 55 d. Steer...

  20. Chromium supplementation alters both glucose and lipid metabolism in feedlot cattle during the receiving period

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crossbred steers (n = 20; 235 +/- 4 kg) were fed 53 days during a receiving period to determine if supplementing chromium (Cr; KemTRACE®brandChromium Propionate 0.04%, Kemin Industries) would alter the glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0...

  1. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of...

  2. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  3. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of...

  4. 77 FR 61431 - Hexavalent Chromium Standards; Extension of the Office of Management and Budget's (OMB) Approval...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-09

    ... Occupational Safety and Health Administration Hexavalent Chromium Standards; Extension of the Office of...) approval of the information collection requirements specified in the Hexavalent Chromium Standards for... requirements specified in the Hexavalent Chromium (Cr(VI)) Standards for General Industry (29 CFR...

  5. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  6. 40 CFR 424.70 - Applicability; description of the electrolytic chromium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... electrolytic chromium subcategory. 424.70 Section 424.70 Protection of Environment ENVIRONMENTAL PROTECTION... Electrolytic Chromium Subcategory § 424.70 Applicability; description of the electrolytic chromium subcategory. The provisions of this subpart are applicable to discharges resulting from the manufacture of...

  7. 40 CFR 721.2097 - Azo chromium complex dyestuff preparation (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Azo chromium complex dyestuff... New Uses for Specific Chemical Substances § 721.2097 Azo chromium complex dyestuff preparation... substance identified generically as an azo chromium complex dyestuff preparation (PMN P-95-240) is...

  8. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject...

  9. 77 FR 32998 - Tin- and Chromium-Coated Steel Sheet From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... COMMISSION Tin- and Chromium-Coated Steel Sheet From Japan Determination On the basis of the record \\1... antidumping duty order on tin- and chromium-coated steel sheet from Japan would be likely to lead to... Commission are contained in USITC Publication 4325 (May 2012), entitled Tin- and Chromium-Coated Steel...

  10. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  11. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  12. 21 CFR 73.3110a - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Chromium-cobalt-aluminum oxide. 73.3110a Section... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3110a Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide (Pigment Blue 36) (CAS Reg....

  13. The Effect of Manganese Additions on the Reactive Evaporation of Chromium in Ni-Cr Alloys

    SciTech Connect

    Holcomb, Gordon R.; Alman, David E.

    2004-10-20

    Chromium is used as an alloy addition in stainless steels and nickel-chromium alloys to form protective chromium oxide scales. Chromium oxide undergoes reactive evaporation in high temperature exposures in the presence of oxygen and/or water vapor. The deposition of gaseous chromium species onto solid oxide fuel cell electrodes can reduce the efficiency of the fuel cell. Manganese additions to the alloy can reduce the activity of chromium in the oxide, either from solid solution replacement of chromium with manganese (at low levels of manganese) or from the formation of manganese-chromium spinels (at high levels of manganese). This reduction in chromium activity leads to a predicted reduction in chromium evaporation by as much as a factor of 35 at 800 C and 55 at 700 C. The results of evaporation loss measurements on nickel-chromium-manganese alloys are compared with the predicted reduction. Quantifying the effects of manganese additions on chromium evaporation should aid alloy development of metallic interconnects and balance-of-plant alloys.

  14. Chromium does not belong in the diabetes treatment arsenal: Current evidence and future perspectives.

    PubMed

    Landman, Gijs Wd; Bilo, Henk Jg; Houweling, Sebastiaan T; Kleefstra, Nanne

    2014-04-15

    Chromium is considered to have positive effects on insulin sensitivity and is marketed as an adjunctive therapy for inducing glucose tolerance in cases of insulin resistance ("the glucose tolerance factor"). Case reports on patients who received prolonged parenteral nutrition indeed showed that the absence of trivalent chromium caused insulin resistance and diabetes. However, whether patients with type 2 diabetes can develop a clinically relevant chromium deficiency is unclear. This review summarizes the available evidence regarding the potential effectiveness of chromium supplementation on glycemic control (Hemoglobin A1c levels) in patients with type 2 diabetes. No studies investigating the long-term safety of chromium in humans were found. All clinical trials that have been performed had a relative short follow-up period. None of the trials investigated whether the patients had risk factors for chromium deficiency. The evidence from randomized trials in patients with type 2 diabetes demonstrated that chromium supplementation does not effectively improve glycemic control. The meta-analyses showed that chromium supplementation did not improve fasting plasma glucose levels. Moreover, there were no clinically relevant chromium effects on body weight in individuals with or without diabetes. Future studies should focus on reliable methods to estimate chromium status to identify patients at risk for pathological alterations in their metabolism associated with chromium deficiency. Given the present data, there is no evidence that supports advising patients with type 2 diabetes to take chromium supplements.

  15. The enzymatic hydrolysis of leather waste with chromium recycling

    SciTech Connect

    Kim, M.S.; Clesceri, L.S.

    1996-11-01

    The work of Taylor et al. (1990) has shown the potential for alkaline hydrolase enzymes for the solubilization of waste from the tanning industry. The authors have carried this work further to examine the mechanism whereby enzymes release chromium from leather waste. An alkaline digest of waste leather was used in this work. Treatment with strong alkali produced a thick slurry that contained 7,000 ppm chromium. The objective of this work is to optimize a closed cycle system for the recycling of chromium salts for tanning as well as a chrome-free product for use as a fertilizer. The authors are able to track the progress of the leather protein hydrolysis with polyacrylamide gel electrophoresis (PAGE). By means of PAGE, it is possible to determine the relationship between chromium release and the extent of protein hydrolysis. Rate constant for hydrolysis and chromium release have been developed for various hydrolysis conditions. Chemical precipitation of chromium from the hydrolysate results in a purified product for reuse in tanning. The chrome-free hydrolysate can be applied as a fertilizer either directly or as a dried product. There are more than 56,000 metric tons of tannery waste produced annually in the US. The majority of the organic solids can be converted into high quality fertilizers. Since the nitrogen is organic rather than inorganic, release is at a controlled rate since the microbody in the soil must make the nitrogen available for plant growth. Leather manufacturing is a world-wide industry. Conversion of leather waste to fertilizers can improve global productivity as well as solve a waste problem.

  16. Bioconcentration and phytotoxicity of chromium in Eichhornia crassipes.

    PubMed

    Mishra, Kumkum; Gupta, Kiran; Rai, Upendra Nath

    2009-07-01

    Physico-chemical parameter and metal concentration in effluents of two industries i.e. Tannery industry, Jajmau, Kanpur and Electroplating industry, Scooter India Limited (SIL), Lucknow were determined to assess the toxicity of chromium. Metal accumulation in Eichhomia crassipes growing in these contaminated sites were also determined. For laboratory toxicity testing the plants were exposed to nutrient solution containing Cr concentration ranging from 0.01-10 microg ml(-1) for 24-96 hr. Accumulation of chromium was observed to be dependent on its concentration and time of exposure and was greater in roots (789.3 mg g(-1) d.wt.) than in leaves (335.6 mg g(-1) d.wt.) after 96 hrat 10 microg ml(-1) concentration. Under field conditions the accumulation of Cr was 1258 and 733.3 in roots and 94 and 53 microg g(-1) d.wt. in leaves of E. crassipes growing in Jajmau, Kanpur tanning industry and SIL effluents, respectively. It was found that lower doses (0.01-0.1 microg ml(-1)) of chromium had stimulatory effect on various metabolic activities in plants including chlorophyll a, b and total chlorophyll, protein, nitrate reductase and mitotic index. Whereas higher doses of chromium had inhibitory effect. The carotenoid content and number of micronuclei was found directly proportional to the concentration of chromium and increased with increase in concentration of chromium to which plants were exposed. It may be concluded from the present study that E. crassipes is tolerant to the elevated Cr concentration as there is no inhibition of chlorophyll and carotenoid up to 0.1 microg ml(-1) at 24 and 48 hr exhibiting phytotoxicity at higher concentration. Therefore, E. crassipes may be used as bioassay for biomonitoring and control of Cr pollution in the environment.

  17. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  18. Effective gain measurements in chromium-doped forsterite

    NASA Technical Reports Server (NTRS)

    Petricevic, V.; Seas, A.; Alfano, R. R.

    1991-01-01

    Effective gain cross section in tetravalent chromium-doped forsterite laser crystal was measured over the 1180-1330 nm spectral range. The experiment was performed using two collinear laser beams in a pump-and-probe arrangement. The peak-gain cross section from this measurement is estimated to be 1.9 x 10 to the -19th sq cm at 1215 nm, which is comparable to the value of about 2 x 10 to the -19th sq cm predicted by fluorescence linewidth and lifetime measurements. These results indicate that excited-state absorption is not a major loss mechanism in tetravalent chromium-doped forsterite.

  19. A review of chromium, molybdenum, and tungsten alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.

    1975-01-01

    The mechanical properties of chromium, molybdenum, and tungsten alloys are reviewed with particular emphasis on high-temperature strength and low-temperature ductility. Precipitate strengthening is highly effective at 0.4 to 0.8 times the melting temperature in these metals, with HfC being most effective in tungsten and molybdenum, and Ta(B,C) most effective in chromium. Low-temperature ductility can be improved by alloying to promote rhenium ductilizing or solution softening. The low-temperature mechanical properties of these alloys appear related to electronic interactions rather than to the usual metallurgical considerations.

  20. Dielectric properties of polyamide 12-chromium(III) oxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Zuev, Vjacheslav V.; Shapoval, Ekaterina S.; Sakhatskii, Aleksandr S.

    2016-08-01

    Broadband dielectric spectroscopy was employed to study polymer nanocomposites based on PA12 filled with of nanosized chromium(III) oxide. The experimental dielectric data were analyzed within the formalisms of complex permittivity and electric modulus. Three relaxation processes and Maxwell-Wagner-Sillars (MWS) interfacial polarizations were observed. It was found that presence of nanosized amphoteric chromium(III) oxide leads to softening of polyamide matrix that manifested in decrease of the activation energy of the α- and β-relaxation processes and glass transition temperatures. The softening of polymer matrix is the reason of the decrease of mechanical strength of polymer nanocomposites as compared with neat PA12.

  1. Use of chitosan for chromium removal from exhausted tanning baths.

    PubMed

    Cesaro, Raffaele; Fabbricino, Massimiliano; Lanzetta, Rosa; Mancino, Anna; Naviglio, Biagio; Parrilli, Michelangelo; Sartorio, Roberto; Tomaselli, Michele; Tortora, Gelsomina

    2008-01-01

    A novel approach, based on chitosan heavy-metal sequestrating ability, is proposed for chromium(III) removal from spent tanning liquor. Experimental results, obtained at lab-scale using real wastewater, are presented and discussed. Resulting efficiencies are extremely high, and strongly dependent on chitosan dose and pH value. Comparative analyses with other polysaccharides is also carried out showing that amine groups are more efficient than carboxyl and sulphate ones. Chromium recovery from sorption complexes and chitosan regeneration is finally proposed to optimize the whole process.

  2. Hot corrosion resistance of nickel-chromium-aluminum alloys

    NASA Technical Reports Server (NTRS)

    Santoro, G. J.; Barrett, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloy was examined by cyclically oxidizing sodium sulfate coated specimens in still air at 900, 1000 and 1100 C. The compositions tested were within the ternary region: Ni; Ni-50 at.% Cr; and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. Corrosion isopleths were prepared from these equations. Compositional regions with the best hot corrosion resistance were identified.

  3. Chromium boron surfaced nickel-iron base alloys

    NASA Technical Reports Server (NTRS)

    Rashid, James M. (Inventor); Friedrich, Leonard A. (Inventor); Freling, Melvin (Inventor)

    1984-01-01

    Chromium boron diffusion coatings on nickel iron alloys uniquely provide them with improvement in high cycle fatigue strength (up to 30%) and erosion resistance (up to 15 times), compared to uncoated alloy. The diffused chromium layer extends in two essential concentration zones to a total depth of about 40.times.10.sup.-6 m, while the succeeding boron layer is limited to 50-90% of the depth of the richest Cr layer nearest the surface. Both coatings are applied using conventional pack diffusion processes.

  4. Nickel and chromium cycles: Stocks and flows project part IV

    NASA Astrophysics Data System (ADS)

    Reck, Barbara K.; Gordon, Robert B.

    2008-07-01

    Nickel and chromium are essential ingredients in alloys increasingly important for energy-efficient, environmentally friendly modern technology. Quantitative assessment of the flows of these metals through the world economy from resource extraction to final disposal informs resource policy, energy planning, environmental science, and waste management. This article summarizes the worldwide technological cycles of nickel and chromium in 2000. Stainless steel is the major use of these metals, but they serve numerous other special needs, as in superalloys for high-temperature service, as plating materials, and in coinage. Because they are used primarily in alloys, novel recycling issues arise as their use becomes more widespread.

  5. Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium

    SciTech Connect

    Steffani, C.; Meltzer, M.

    1995-04-01

    Chromium, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome.

  6. Hydrolytic polymerization of chromium (III). 2. A trimeric species

    SciTech Connect

    Finholt, J.E.; Thompson, M.E.; Connick, R.E.

    1981-12-01

    With use of an ion-exchange displacement elution, a green species was separated from mixtures of Cr(III) polymers and its absorption spectrum determined. The hydroxides per chromium atom were found to be 4/3, and the charge per chromium atom was shown to be consistent with this value. The degree of polymerization of freezing point depression was close to 3. Measurements are reported for the equilibrium quotient for the formation of the trimer from the monomer. The ESR spectrum and magnetic susceptibility were determined, and the results are discussed in terms of possible structures.

  7. Electrical Resistivity of Chromium, Cobalt, Iron, and Nickel.

    DTIC Science & Technology

    1982-06-01

    Desai, P.D., Thermal Expansion-Metallic Elements and Alloys , Vol. 12 of Thermophysical Properties of Matter - The TPRC Data Series ( Touloukian , Y.S. and...Phys. Met. Metallogr., 16(6), 134-5, 1963. 46. Levin, E.S., Gel’d, P.V., and Aynshina, G.D., "Electrical Conductivity of Molten Chromium Aluminum Alloys ...Phys. Chem., 43(11), 1542-5, 1969. 57. Levin, E.S., "Determination of Some Physico-Chemical Properties of Chromium- Aluminum Melts," Izv. Akad. Nauk

  8. Fertilizers and Mixed Crop Cultivation of Chromium Tolerant and Sensitive Plants under Chromium Toxicity

    PubMed Central

    Dheeba, B.; Sampathkumar, P.; Kannan, K.

    2015-01-01

    Zea mays (maize) and Vigna radiata (green gram) are found to be the chromium (Cr) tolerant and sensitive plants, respectively. In the present paper, we investigate the reduction of the toxicity of Cr in the sensitive plants by the mixed crop cultivation in the field using various amendments. Further, the potassium dichromate was used as the source of hexavalent Cr. The results indicated that Cr adversely affects both the growth and yield of plants. The soil properties vary with Cr and different fertilizer amendments and the yield of both plants were affected by Cr. We conclude that metal accumulation of seeds of green gram was higher than corn and the application of single fertilizer either farm yard manure (FYM) or nitrogen, phosphorous, and potassium (NPK) enhances the growth and yield of both the tolerant and sensitive plants in the mixed crop cultivations. PMID:25709647

  9. Reaction diffusion in the nickel-chromium-aluminum and cobalt-chromium-aluminum systems

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1977-01-01

    The effects of MCrAl coating-substrate interdiffusion on oxidation life and the general mutliphase, multicomponent diffusion problem were examined. Semi-infinite diffusion couples that had sources representing coatings and sinks representing gas turbine alloys were annealed at 1,000, 1,095, 1,150, or 1,205 C for as long as 500 hours. The source and sink aluminum and chromium contents and the base metal (cobalt or nickel) determined the parabolic diffusion rate constants of the couples and predicted finite coating lives. The beta source strength concept provided a method (1) for correlating beta recession rate constants with composition; (2) for determining reliable average total, diffusion, and constitutional activation energies; and (3) for calculating interdiffusion coefficients.

  10. Increasing total and biologically active chromium in wheat grain and spinach by spraying with chromium salts

    SciTech Connect

    Vicini, F.A.; Ellis, B.G.

    1981-06-01

    Recently, chromium has been shown to be necessary for glucose metabolism in man. But most plant species greatly restrict the uptake of Cr. This study was conducted to determine if both total and biologically active Cr could be increased in wheat grain or spinach by spraying the plants with either Cr/sub 2/(SO/sub 4/)/sub 3/ or Cr-EDTA. Concentrations of Cr in wheat grain were about doubled in a greenhouse experiment by spraying with either Cr source. Biologically active Cr (estimated by extraction with ethanol or NH/sub 4/OH) was increased from about 40 to greater than 50% of total Cr when wheat was sprayed with Cr salts. Total Cr in spinach leaves was increased by as much as 10-fold by spraying, with the sulfate source being more effective than the EDTA.

  11. Reducing chromium losses from a chromium plating bath. 1987 summer intern report. Project conducted at New Dimension Plating, Hutchinson, Minnesota

    SciTech Connect

    Achman, D.

    1987-12-31

    The company employs about forty people and operates for one or two eight hour shifts with an average of 315 racks of chrome plating per eight hour day. They plate a variety of metals including copper, nickel, gold, brass and chromium. Chromium is the major metal plated and is usually the last step in plating cycle. Most parts are copper plated and then nickel plated in preparation for chrome plating. The main difference between New Dimension Plating and other plating shops is the variety of parts plated. As New Dimension Plating is a job shop, a wide range of parts such as motorcycle accessories, stove parts, and custom items are metal finished. The plating lines are manual, meaning employees dip the racks into the tanks by hand. This fact along with the fact that parts vary greatly in size and shape accounts for the significant drag-out on the chromium plating line.

  12. Interferences in the spectrophotometric S-diphenylcarbazide determination of environmental hexavalent chromium in a chromium and zinc plating plant.

    PubMed

    Carelli, G; La Bua, R; Rimatori, V; Porcelli, D; Iannaccone, A

    1981-03-01

    A study on the determination of environmental hexavalent chromium [Cr(VI)] was carried out in a chromium and zinc plating plant. The atmospheric particulate was collected both on glass wool filters and with an electrostatic sampler; Cr(VI) was determined by the S-diphenylcarbazide method. The filtered and electrostatically collected Cr(VI) was extracted with both 1.4% sulfuric acid and 7% sodium carbonate. Strong interference was observed when extraction was carried out with the acid medium. Alkaline extraction permits 95 +/- 6 (+/- SD)% recovery of the total chromium and has been shown to be suitable in releasing Cr(VI). The analyses of the alkaline samples were carried out with the standard addition method to compensate for a depressive interference of 26 +/- 8 (+/- SD)%. The absorbance decrease of the Cr-S-diphenylcarbazide complex is a time function, and it should be measured within a few minutes of the reagent addition.

  13. Effect of chromium salts on invertase immobilization onto carboxymethyl-cellulose-gelatine carrier system.

    PubMed

    Emregül, E; Sungur, S; Akbulut, U

    1996-07-01

    The carboxymethylcellulose-gelatine carrier system was investigated for invertase immobilization. Chromium (III) acetate, chromium (III) sulphate and potassium chromium (III) sulphate were used as cross-linking agents. Effect of carboxymethylcellulose-gelatine ratio and cross-linker concentration on immobilized enzyme activity were analysed. Reusability of immobilized enzyme was also investigated. Maximum immobilized enzyme activities were obtained with cross-linkers chromium (III) sulphate (0.004 mol dm-3) and potassium chromium (III) sulphate (0.001 mol dm-3) for a carrier composition of carboxymethylcellulose-gelatine ratio 0.111 (w/w) as 78%.

  14. Reactor target from metal chromium for "pure" high-intensive artificial neutrino source

    NASA Astrophysics Data System (ADS)

    Gavrin, V. N.; Kozlova, Yu. P.; Veretenkin, E. P.; Logachev, A. V.; Logacheva, A. I.; Lednev, I. S.; Okunkova, A. A.

    2017-01-01

    The paper presents the first results of development of manufacturing technology of metallic chromium targets from highly enriched isotope 50Cr for irradiation in a high flux nuclear reactor to obtain a compact high intensity neutrino source with low content of radionuclide impurities and minimum losses of enriched isotope. The main technological stages are the hydrolysis of chromyl fluoride, the electrochemical reduction of metallic chromium, the hot isostatic pressing of chromium powder and the electrical discharge machining of chromium bars. The technological stages of hot isostatic pressing of chromium powder and of electrical discharge machining of Cr rods have been tested.

  15. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  16. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  17. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  18. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Chromium (Cr III) complex of N-ethyl-N... § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium... by weight of the chromium (Cr III) complex of heptadecylfluoro-octane sulfonic acid may be...

  19. The chromium accumulation and its physiological effects in juvenile rockfish, Sebastes schlegelii, exposed to different levels of dietary chromium (Cr(6+)) concentrations.

    PubMed

    Kim, Jun-Hwan; Kang, Ju-Chan

    2016-01-01

    Juvenile rockfish (mean length 13.7±1.7 cm, and mean weight 55.6±4.8 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr(6+)) at 0, 30, 60, 120 and 240 mg/kg. The profile of chromium in the tissues of rockfish is dependent on the exposure periods and chromium concentration. After 4 weeks, the order of chromium accumulation in tissues was liver>kidney>spleen>intestine>gill>muscle. The dietary chromium exposure decreased the growth rate and hepatosomatic index of rockfish. The major hematological findings were significant decrease in the red blood cell (RBC) count, hematocrit (Ht) value, and hemoglobin (Hb) concentration exposed to ≥120 mg/kg chromium concentrations. The dietary chromium exposure (≥120 mg/kg) led to notable increase in glucose, cholesterol, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) in plasma, whereas there was no considerable change in calcium, magnesium, total protein, and alkaline phosphatase (ALP). The results indicated that the dietary chromium exposure to rockfish can induce significant chromium accumulation in the specific tissues, inhibition of growth, and hematological alterations.

  20. Chromium(VI) transport and fate in unsaturated zone and aquifer: 3D Sandbox results.

    PubMed

    Zhao, Xingmin; Sobecky, Patricia A; Zhao, Lanpo; Crawford, Patrice; Li, Mingtang

    2016-04-05

    The simulation of Cr(VI) behavior in an unsaturated zone and aquifer, using a 3D experimental set-up were performed to illustrate the distribution, transport and transformation of Cr(VI), and further to reveal the potential harm of Cr(VI) after entering the groundwater. The result indicated that chromium(VI) was transported in the vertical direction, meanwhile, was transported in the horizontal direction under the influence of groundwater flow. The direction and distance away from the pollution source zone had great effect on the chromium(VI) concentration. At the sampling sites near the pollution source zone, there was a sudden increase of chromium(VI) concentration. The concentration of chromium(III) concentration in some random effluent samples was not detected. Chromium had not only transported but also had fraction and specie transformation in the unsaturated zone and aquifer. The relative concentration of residue fraction chromium was decreased with time. The content of Fe-Mn oxide fraction chromium was increased with time. The relative content of exchangeable and carbonate-bound fraction chromium was lower and the content variations were not obvious. Chromium(VI) (91-98%) was first reduced to chromium(III) rapidly. The oxidation reaction occurred later and the relative content of chromium(VI) was increased again. The presence of manganese oxides under favorable soil conditions can promote the reoxidation of Cr(III) to Cr(VI).

  1. The effect of chromium picolinate on serum cholesterol and apolipoprotein fractions in human subjects.

    PubMed Central

    Press, R. I.; Geller, J.; Evans, G. W.

    1990-01-01

    Chromium has been implicated as a cofactor in the maintenance of normal lipid and carbohydrate metabolism. A deficiency of chromium results from diets low in biologically available chromium. Picolinic acid, a metabolite of tryptophan, forms stable complexes with transitional metal ions, which results in an improved bioavailability of the metal ion chromium. To determine whether or not chromium picolinate is effective in humans, 28 volunteer subjects were given either chromium tripicolinate (3.8 micromol [200 micrograms] chromium) or a placebo daily for 42 days in a double-blind crossover study. A 14-day period off capsules was used between treatments. Levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and apolipoprotein B, the principal protein of the LDL fraction, decreased significantly while the subjects were ingesting chromium picolinate. The concentration of apolipoprotein A-I, the principal protein of the high-density lipoprotein (HDL) fraction, increased substantially during treatment with chromium picolinate. The HDL-cholesterol level was elevated slightly but not significantly during ingestion of chromium picolinate. Only apolipoprotein B, of the variables measured, was altered significantly during supplementation with the placebo. These observations show that chromium picolinate is efficacious in lowering blood lipids in humans. PMID:2408233

  2. Magnetic Exchange Interactions in the Linear Chain Chromium (III) Compounds Catena-Fluorophthalocyaninato chromium (III) and Catena-Cyanophthalocyaninato chromium (III).

    DTIC Science & Technology

    2014-09-26

    to JAF which are the predominant exchange interactions in fluoro-bridged [CrPcF]n. Exchange in (CrPcCN]n. The electronic configuration of the cyanide ...The coordination of cyanide to metal ions is stabilized by dative X bonding. In this particular case, there is the possibility for dative X bonding...between chromiu~m(III) and * cyanide which involves the KX y orbitals of cyanide and xz, yz orbitals of chromium. This bonding interaction is much greater

  3. Moss biomonitoring of air pollution with chromium in Croatia.

    PubMed

    Vučković, Ivana; Spirić, Zdravko; Stafilov, Trajče; Kušan, Vladimir

    2013-01-01

    The purpose of this study was to determine the atmospheric deposition of chromium in Croatia by using moss biomonitoring technique and atomic emission spectrometry with inductively coupled plasma (ICP-AES). Moss samples (Hylocomium splendens, Hypnum cupressiforme, Brachythecium rutabulum and Homalothecium Sericeum) were collected from 121 sampling sites evenly distributed over the country, during the summer and autumn of 2010. Collected samples were air dried, then cleaned and digested by using microwave digestion system. The median value obtained in this study (1.94 mg kg⁻¹) compared with the median value of previous investigation performed in 2006 (2.75 mg kg⁻¹) shows that the content of chromium decreased. Higher contents of chromium were found in moss samples collected in the regions of Central Croatia, in/near the cities of Zagreb, Sisak and Kutina, which, in the most of the cases, are result of anthropogenic activities. In Costal Croatia, higher values have a natural origin due to the significantly higher content of Cr in soil from this region. The results were compared with those from similar studies in neighboring and other Balkan countries. It was established that the content of chromium in Croatia is lower than in the most of these countries.

  4. New alloys to conserve critical elements. [replacing chromium in steels

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.

    1978-01-01

    Previous studies and surveys on availability of domestic reserves have shown that chromium is a most critical element within the U.S. metal industry. More precisely, the bulk of chromium is consumed in the production of stainless steels, specifically Type 304 stainless steel (304SS) which contains 18% Cr. The present paper deals with means of reducing chromium in commercial stainless steels by substituting more abundant or less expensive elements with the intent of maintaining the properties of 304SS. The discussion focuses on some of the oxidation and corrosion properties of new substitute stainless steels with only 12% Cr, which represents a potential saving of 33% of the chromium consumed in the production of 304SS. The alloying elements substituted for Cr in 304SS are selected according to their potential for protective oxide formation during high-temperature oxidation; these are Al, Si, Ti, Y, and misch metal which is 99.7% rare-earth metals containing 50 to 55% cerium. Other alloying elements to impart corrosion resistance are Mn, Mo, and V.

  5. Extended followup of a cohort of chromium production workers

    PubMed Central

    Lees, Peter St. John; Wang, Jing; Grace O'Leary, Keri

    2015-01-01

    Background The current study evaluates the mortality of 2,354 workers first employed at a Baltimore chromate production plant between 1950 and 1974. Methods The National Death Index (NDI Plus) was used to determine vital status and cause of death. Cumulative chromium (VI) exposure and nasal and skin irritation were evaluated as risk factors for lung cancer mortality. Results There are 91,186 person‐years of observation and 217 lung cancer deaths. Cumulative chromium (VI) exposure, nasal irritation, nasal perforation, nasal ulceration, and other forms of irritation (e.g., skin irritation) were associated with lung cancer mortality. Conclusion Cumulative chromium (VI) exposure was a risk factor for lung cancer death. Cancer deaths, other than lung cancer, were not significantly elevated. Irritation may be a possible mechanism for chromium (VI)‐induced lung cancer. Am. J. Ind. Med. 58:905–913, 2015. © 2015 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc. PMID:26041683

  6. Chromium-Catalyzed Asymmetric Dearomatization Addition Reactions of Halomethyl Heteroarenes.

    PubMed

    Tian, Qingshan; Bai, Jing; Chen, Bin; Zhang, Guozhu

    2016-04-15

    The first asymmetric dearomatization addition reaction of halomethyl arenes including benzofuran and benzothiophene was enabled by chromium catalysis. A variety of aldehydes served as suitable electrophiles under mild reaction conditions. Molecular complexities are quickly increased in a highly diastereo- and enantioselective manner.

  7. IRIS TOXICOLOGICAL REVIEW OF HEXAVALENT CHROMIUM (INTERAGENCY SCIENCE CONSULTATION DRAFT)

    EPA Science Inventory

    On Septemeber 30, 2010, the draft Toxicological Review of Hexavalent Chromium and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agenc...

  8. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... drug application, pursuant to section 505 of the Federal Food, Drug, and Cosmetic Act, is in effect for... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  9. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... drug application, pursuant to section 505 of the Federal Food, Drug, and Cosmetic Act, is in effect for... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73.1015 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  10. 21 CFR 73.3111 - Chromium oxide greens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Chromium oxide greens. 73.3111 Section 73.3111 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... required to accomplish the intended coloring effect. (2) Authorization and compliance with this use...

  11. 21 CFR 73.3111 - Chromium oxide greens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Chromium oxide greens. 73.3111 Section 73.3111 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... required to accomplish the intended coloring effect. (2) Authorization and compliance with this use...

  12. Chromium ion plating studies for enhancement of bearing lifetime

    NASA Technical Reports Server (NTRS)

    Davis, J. H.

    1982-01-01

    Six 440-C hardened stainless steel roller bearing test rods were ion plated with various chromium films of thicknesses from .2 microns to 7 microns. The thinner (approximately .2 microns) coating sample had 3 times the fatigue life of the unplated (standard) specimens. Contrastingly, the samples having thicker coatings (several microns) had short fatigue lives (about 3% of the unplated standard).

  13. Chromium toxicity to nitrifying bacteria: implications to wastewater treatment

    EPA Science Inventory

    Chromium, a heavy metal that enters wastewater treatment plants (WWTPs) through industrial discharges, can be toxic to microorganisms carrying out important processes within biological wastewater treatment systems. The effect of Cr(III) and Cr(VI) on ammonia dependent specific ox...

  14. Ailanthus Altissima and Phragmites Australis for chromium removal from a contaminated soil.

    PubMed

    Ranieri, Ezio; Fratino, Umberto; Petrella, Andrea; Torretta, Vincenzo; Rada, Elena Cristina

    2016-08-01

    The comparative effectiveness for hexavalent chromium removal from irrigation water, using two selected plant species (Phragmites australis and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. Total chromium removal from water was ranging from 55 % (Phragmites) to 61 % (Ailanthus). After 360 days, the contaminated soil dropped from 70 (initial) to 36 and 41 mg Cr/kg (dry soil), for Phragmites and Ailanthus, respectively. Phragmites accumulated the highest amount of chromium in the roots (1910 mg Cr/kg(dry tissue)), compared with 358 mg Cr/kg(dry tissue) for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Cr(VI) reduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems. Both plant species showed good potentialities to be used in phytoremediation installations for chromium removal.

  15. Controlling chromium slag pollution utilising scavengers: a case of Shandong Province, China.

    PubMed

    Liu, Changhao; Côté, Raymond P

    2015-04-01

    The problem of chromium slag pollution is a great challenge for China. It is now an urgent task for China to take effective measures to eliminate chromium slag pollution. This article examines the case of the treatment of chromium slag in Shandong Province and explores how chromium slag pollution can be eliminated in Shandong Province. It shows that the chromium slag stockpiled by the chemical plants was successfully utilised by local steel companies, who act as 'scavenger companies'. The driving mechanism, seeking a potential 'scavenger company' within the local region and the role of the local government on the case of Shandong Province are discussed. This article concludes that local steel companies can be utilised to effectively and efficiently treat the chromium slag while benefiting the steel companies. The local governments need to play multiple roles in solving the problem of chromium slag pollution. Seeking and identifying 'scavenger companies' within a region could be an important approach to reducing pollution within the region.

  16. Electrochemical removal of chromium from waste water. Rept. for 20 Jul 91-19 May 92

    SciTech Connect

    Prentice, G.; Wilson, T.; Walker, C.

    1992-07-15

    The authors carried out a study to determine the feasibility of electrochemically removing chromium from plating wastewater. Hexavalent chromium is a carcinogen and its discharge is required to be near 1 ppm. In this work they determined the effects of key variables including temperature, electrolyte flow rate, pH, and electrode composition. At the low chromium concentrations found in plating wastewater, they determined that the rate of chromium ion removal was mass transfer limited. Of the four electrode types tested, only gold gave significantly enhanced performance; however, graphite would probably be the most cost-effective for large-scale application. Chromium reduction rate was significantly increased at reduced pH. Because chromium ion solubility increases at lower pH, the higher removal rate would need to to be balanced against higher chromium redissolution rate in a practical system. A preliminary analysis based on the laboratory data indicates that a practical system based on electrochemical technology is feasible.

  17. Development of ductile high-strength chromium alloys, phase 2

    NASA Technical Reports Server (NTRS)

    Filippi, A. M.

    1973-01-01

    Strength and ductility were evaluated for chromium alloys dispersion hardened with the putative TaC, TaB, CbC, and CbB compounds. TaC and TaB proved to be the most potent strengtheners, but when combined, their effect far outweighed that produced individually. Tests at 1422 K (2100 F) on an alloy containing these two compounds at the combined level of 0.5 m/o revealed a 495 MN/sq m (70 ksi) tensile strength for wrought material, and a 100 hour rupture strength of 208 MN/sq m (30 ksi) when solution annealed and aged to maximize creep resistance. These levels of high temperature strength greatly exceed that reported for any other chromium-base alloy. The ductile-to-brittle transition temperature (DBTT) of the two phase strengthened alloy occurred at approximately 588 K (600 F) when heat treated to optimize creep strength and was not improved by fabrication to produce a wrought and recovered microstructure. The lowest DBTT measured on any of the alloys investigated was 422 K (300 F). Strengthening phases actually formed in Cr-Ta-B and Cr-Cb-B compositions are probable M2CrB2 (M=Ta or Cb) compounds of tetragonal crystal structure. The likely habit relationship between these compounds and chromium is postulated. Cube habit coherency was identified for TaC precipitation in chromium by electron microscopy. In another study, the maximum solubility of carbon in chromium was indicated to lie between 3/4 and 1 a/o and that of boron to be 1/2 a/o.

  18. Arsenic and chromium topsoil levels and cancer mortality in Spain.

    PubMed

    Núñez, Olivier; Fernández-Navarro, Pablo; Martín-Méndez, Iván; Bel-Lan, Alejandro; Locutura, Juan F; López-Abente, Gonzalo

    2016-09-01

    Spatio-temporal cancer mortality studies in Spain have revealed patterns for some tumours which display a distribution that is similar across the sexes and persists over time. Such characteristics would be common to tumours that shared risk factors, including the chemical soil composition. The objective of the present study is to assess the association between levels of chromium and arsenic in soil and the cancer mortality. This is an ecological cancer mortality study at municipal level, covering 861,440 cancer deaths in 7917 Spanish mainland towns from 1999 to 2008. Chromium and arsenic topsoil levels (partial extraction) were determined by ICP-MS at 13,317 sampling points. To estimate the effect of these concentrations on mortality, we fitted Besag, York and Mollié models, which included, as explanatory variables, each town's chromium and arsenic soil levels, estimated by kriging. In addition, we also fitted geostatistical-spatial models including sample locations and town centroids (non-aligned data), using the integrated nested Laplace approximation (INLA) and stochastic partial differential equations (SPDE). All results were adjusted for socio-demographic variables and proximity to industrial emissions. The results showed a statistical association in men and women alike, between arsenic soil levels and mortality due to cancers of the stomach, pancreas, lung and brain and non-Hodgkin's lymphomas (NHL). Among men, an association was observed with cancers of the prostate, buccal cavity and pharynx, oesophagus, colorectal and kidney. Chromium topsoil levels were associated with mortality among women alone, in cancers of the upper gastrointestinal tract, breast and NHL. Our results suggest that chronic exposure arising from low levels of arsenic and chromium in topsoil could be a potential risk factor for developing cancer.

  19. Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

    USGS Publications Warehouse

    Izbicki, J.A.; Ball, J.W.; Bullen, T.D.; Sutley, S.J.

    2008-01-01

    Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 ??g/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 ??g/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 ??g/L at pH < 7.5 regardless of geology. ??53Cr values in native ground-water ranged from 0.7 to 5.1??? and values were fractionated relative to the average ??53Cr composition of 0??? in the earth's crust. Positive ??53Cr values of 1.2 and 2.3??? were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. ??53Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing ??53Cr values were observed as dissolved O2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest ??53Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. ??53Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from -0.1 to 3.2???. Near zero ??53Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased ??53Cr values at the site. Although ??53Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the ??53Cr values in conjunction with major-ion data, and the ??18O and ??D composition of water from wells.

  20. Trace Element Status (Iron, Zinc, Copper, Chromium, Cobalt, and Nickel) in Iron-Deficiency Anaemia of Children under 3 Years

    PubMed Central

    Angelova, Maria Georgieva; Petkova-Marinova, Tsvetelina Valentinova; Pogorielov, Maksym Vladimirovich; Loboda, Andrii Nikolaevich; Nedkova-Kolarova, Vania Nedkova; Bozhinova, Atanaska Naumova

    2014-01-01

    Aim. To determine trace element status and aetiologic factors for development of trace elements deficiencies in children with iron-deficiency anaemia (IDA) aged 0 to 3 years. Contingent and Methods. 30 patients of the University Hospital, Pleven, Bulgaria—I group; 48 patients of the Sumy Regional Child's Clinical Hospital, Sumy, Ukraine—II group; 25 healthy controls were investigated. Serum concentrations of iron, zinc, copper, chromium, cobalt, and nickel were determined spectrophotometrically and by atomic absorption spectrophotometry. Results. Because the obtained serum levels of zinc, copper, and chromium were near the lower reference limits, I group was divided into IA and IB. In IA group, serum concentrations were lower than the reference values for 47%, 57%, and 73% of patients, respectively. In IB group, these were within the reference values. In II group, results for zinc, cobalt, and nickel were significantly lower (P < 0.05), and results for copper were significantly higher in comparison to controls. Conclusion. Low serum concentrations of zinc, copper, cobalt, and nickel were mainly due to inadequate dietary intake, malabsorption, and micronutrient interactions in both studied groups. Increased serum copper in II group was probably due to metabolic changes resulting from adaptations in IDA. Data can be used for developing a diagnostic algorithm for IDA. PMID:24839556

  1. Bioadsorption and bioaccumulation of chromium trivalent in Cr(III)-tolerant microalgae: a mechanisms for chromium resistance.

    PubMed

    Pereira, M; Bartolomé, M C; Sánchez-Fortún, S

    2013-10-01

    Anthropogenic activity constantly releases heavy metals into the environment. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. While hexavalent chromium uptake in plant cells has been reported that an active process by carrying essential anions, the cation Cr(III) appears to be taken up inactively. Dictyosphaerium chlorelloides (Dc1M), an unicellular green alga is a well-studied cell biological model organism. The present study was carried out to investigate the toxic effect of chromium exposures on wild-type Cr(III)-sensitive (Dc1M(wt)) and Cr(III)-tolerant (Dc1M(Cr(III)R30)) strains of these green algae, and to determine the potential mechanism of chromium resistance. Using cell growth as endpoint to determine Cr(III)-sensitivity, the IC₅₀(₇₂) values obtained show significant differences of sensitivity between wild type and Cr(III)-tolerant cells. Scanning electron microscopy (SEM) showed significant morphological differences between both strains, such as decrease in cell size or reducing the coefficient of form; and transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization and cell wall thickening in the Cr(III)-tolerant strain with respect to the wild-type strain. Energy dispersive X-ray analysis (SEM/XEDS) revealed that Cr(III)-tolerant D. chlorelloides cells are able to accumulate considerable amounts of chromium distributed in cell wall (bioadsorption) as well as in cytoplasm, vacuoles, and chloroplast (bio-accumulation). Morphological changes of Cr(III)-tolerant D. chlorelloides cells and the presence of these electron-dense bodies in their cell structures can be understood as a Cr(III) detoxification mechanism.

  2. Urinary levels of nickel and chromium associated with dental restoration by nickel-chromium based alloys.

    PubMed

    Chen, Bo; Xia, Gang; Cao, Xin-Ming; Wang, Jue; Xu, Bi-Yao; Huang, Pu; Chen, Yue; Jiang, Qing-Wu

    2013-03-01

    This paper aims to investigate if the dental restoration of nickel-chromium based alloy (Ni-Cr) leads to the enhanced excretions of Ni and Cr in urine. Seven hundred and ninety-five patients in a dental hospital had single or multiple Ni-Cr alloy restoration recently and 198 controls were recruited to collect information on dental restoration by questionnaire and clinical examination. Urinary concentrations of Ni and Cr from each subject were measure by graphite furnace atomic absorption spectrometry. Compared to the control group, the urinary level of Ni was significantly higher in the patient group of <1 month of the restoration duration, among which higher Ni excretions were found in those with either a higher number of teeth replaced by dental alloys or a higher index of metal crown not covered with the porcelain. Urinary levels of Cr were significantly higher in the three patient groups of <1, 1 to <3 and 3 to <6 months, especially in those with a higher metal crown exposure index. Linear curve estimations showed better relationships between urinary Ni and Cr in patients within 6-month groups. Our data suggested significant increased excretions of urinary Ni and Cr after dental restoration. Potential short- and long-term effects of Ni-Cr alloy restoration need to be investigated.

  3. Evaluation of the comprehensiveness and reliability of the chromium composition of foods in the literature ☆

    PubMed Central

    Thor, Mayly Y.; Harnack, Lisa; King, Denise; Jasthi, Bhaskarani; Pettit, Janet

    2011-01-01

    In the early 1960s, trivalent chromium Cr3+ became recognized as an essential trace element due to its potential metabolic and cardiovascular benefits. No comprehensive chromium database currently exists; thus a thorough review of the literature was conducted to examine the availability and reliability of chromium data for foods. A number of key issues were identified that challenge the feasibility of adding chromium to a food and nutrient database. Foremost, dietary chromium data reported in the literature prior to 1980 cannot be relied on because of problematic analytical issues before that time. Next, paucity of data emerged as an issue that could impede database completeness. Finally, large variation in reported chromium content of foods may render disputable representative chromium values. This variation has been speculated to originate from differences in growing and particularly processing foods. Furthermore, contamination of chromium from laboratory equipment and/or materials is possible and also believed to contribute to the variation observed in reported values. As a result, database developers must carefully consider the availability and reliability of information on the chromium composition of foods when deciding whether to incorporate chromium into or exclude it from a nutrient database. PMID:23066174

  4. Effect of Chromium on Microstructure and Properties of High Boron White Cast Iron

    NASA Astrophysics Data System (ADS)

    Liu, Zhongli; Chen, Xiang; Li, Yanxiang; Hu, Kaihua

    2008-03-01

    In this article, the effect of chromium on microstructure and properties of high boron white cast iron was studied. The results indicate that the microstructure of high boron white cast iron with different chromium content comprises a dendritic matrix and interdendritic eutectics, and the eutectic compound has a M2B-type chemical formula that does not change with the difference of chromium content. The increase of chromium not only increases the microhardness of boride, but also improves the morphology of boride, which is changed from continuous network to less continuous distribution. Moreover, with the chromium increase, martensite appears in the matrix under the as-cast condition, the appearance of which depends on the increase of chromium in the matrix and the uneven distribution of carbon in the matrix caused by chromium addition. After quenching in air, the matrixes of alloys all change to martensite. However, some secondary particles are found in the central area of the dendrite grains of alloys with higher chromium, and their existence is due to the difference of boron solubility in the matrix with different chromium content. In addition, the hardenability, hardness, and impact toughness are all improved with the increase in chromium.

  5. Maximum availability and mineralogical control of chromium released from AOD slag.

    PubMed

    Li, Junguo; Liu, Bao; Zeng, Yanan; Wang, Ziming; Gao, Zhiyuan

    2017-03-01

    AOD (argon oxygen decarburization) slag is the by-product in the stainless steel refining process. Chromium existing in AOD slag can leach out and probably poses a serious threat to the environment. To assess the leaching toxicity of chromium released from AOD slag, the temperature-dependent maximum availability leaching test was performed. To determine the controlling mineralogical phases of chromium released from AOD slag, a Visual MINTEQ simulation was established based on Vminteq30 and the FactSage 7.0 database. The leaching tests indicated that the leaching availability of chromium was slight and mainly consisted of trivalent chromium. Aging of AOD slag under the atmosphere can oxidize trivalent chromium to hexavalent chromium, which could be leached out by rainwater. According to the simulation, the chromium concentration in leachates was controlled by the freely soluble pseudo-binary phases in the pH = 7.0 leaching process and controlled by the Cr2O3 phase in the pH = 4.0 leaching process. Chromium concentrations were underestimated when the controlling phases were determined to be FeCr2O4 and MgCr2O4. Facilitating the generation of the insoluble spinel-like phases during the cooling and disposal process of the molten slag could be an effective approach to decreasing the leaching concentration of chromium and its environmental risk.

  6. STS-47 Crew Briefing

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The crew of STS-47, Commander Robert L. Gibson, Pilot Curtis L. Brown, Payload Commander Mark C. Lee, Mission Specialists N. Jan Davis, Jay Apt, and Mae C. Jemison, and Payload Specialist Mamoru Mohri answer questions from the press about the upcoming Endeavour mission and the crew's personal views of the mission.

  7. Acute toxicity by water containing hexavalent or trivalent chromium in native Brazilian fish, Piaractus mesopotamicus: anatomopathological alterations and mortality.

    PubMed

    Castro, Marcello Pardi; de Moraes, Flávio Ruas; Fujimoto, Rodrigo Yudi; da Cruz, Claudinei; Belo, Marco Antonio de Andrade; de Moraes, Julieta Rodini Engrácia

    2014-02-01

    This study evaluated the toxicity of hexavalent and trivalent compounds of chromium to the pacu, Piaractus mesopotamicus, in acute exposures of 96 h through mortality and histopathological responses. Hexavalent potassium dichromate was more toxic than trivalent compounds of chromium chloride, chromium oxide and chromium carbochelate. Sufficient mortalities occurred only with potassium dichromate to yield an LC50 value at 124.2 mg L(-1). Hexavalent chromium caused reversible and irreversible lesions, which may affect organ functionality. Histopathological evaluation showed that trivalent chromium caused lesions of lower severity. Pacu subjected to different concentrations of chromium carbochelate showed no histopathological changes in the kidneys, liver, skin and gills, being similar to those of the control fish. Among the three sources of Cr(3+), only chromium chloride at 200 mg L(-1) resulted in mortality, which reached 100 % within the first 18 h. These findings confirm that trivalent chromium, when administered within recommended levels, may be used safely in aquaculture.

  8. Study of the Thermodynamics of Chromium(III) and Chromium(VI) Binding to Fe3O4 and MnFe2O4 nanoparticles

    PubMed Central

    Luther, Steven; Brogfeld, Nathan; Kim, Jisoo; Parsons, J.G.

    2013-01-01

    Removal of chromium(III) or (VI) from aqueous solution was achieved using Fe3O4, and MnFe2O4 nanomaterials. The nanomaterials were synthesized using a precipitation method and characterized using XRD. The size of the nanomaterials was determined to be 22.4 ± 0.9 nm (Fe3O4) and 15.5 ± 0.5 nm (MnFe2O4). The optimal binding pH for chromium(III) and chromium(VI) were pH 6 and pH 3. Isotherm studies were performed, under light and dark conditions, to determine the capacity of the nanomaterials. The capacities for the light studies with MnFe2O4 and Fe3O4 were determined to be 7.189 and 10.63 mg/g, respectively, for chromium(III). The capacities for the light studies with MnFe2O4 and Fe3O4 were 3.21 and 3.46 mg/g, respectively, for chromium(VI). Under dark reaction conditions the binding of chromium(III) to the MnFe2O4 and Fe3O4 nanomaterials were 5.74 and 15.9 mg/g, respectively. The binding capacity for the binding of chromium(VI) to MnFe2O4 and Fe3O4 under dark reaction conditions were 3.87 and 8.54 mg/g, respectively. The thermodynamics for the reactions showed negative ΔG values, and positive ΔH values. The ΔS values were positive for the binding of chromium(III) and for chromium(VI) binding under dark reaction conditions. The ΔS values for chromium(VI) binding under the light reaction conditions were determined to be negative. PMID:23558081

  9. Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide.

    PubMed

    Pillay, K; von Blottnitz, H; Petersen, J

    2003-09-01

    Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, utilisation or controlled disposal of such slag is generally considered unproblematic. Experimental test work with a number of slag materials indicates, however, that very gradual oxidation of trivalent to hexavalent chromium does occur when the slag is exposed to atmospheric oxygen, rendering a quantifiable but small portion of chromium in this much more mobile and toxic form. Mechanisms and rates of the oxidation reaction were investigated in a number of long-term studies using both original slag materials and artificial mixes of chromium and calcium oxides. Powders of these materials, some of them rolled into balls, were left to age under different conditions for periods of up to 12 months. In the slag samples, which contained between 1 and 3 wt.% chromium, 1000-10000 microg Cr(VI) were found per gram of chromium within 6-9 months of exposure to an ambient atmosphere. The rate of the oxidation reaction decreased exponentially, and the reaction could generally be said to have ceased within 12 months. In mixtures of calcium and chromium oxides the oxidation reaction is presumed to occur at the boundaries between chromium oxide and calcium oxide phases through diffusion of oxygen along the grain boundaries and of Cr(3+) across the boundaries, resulting in the formation of calcium chromate. In the slags, where calcium and chromium oxide can form a solid solution, the oxidation is likely to occur at the exposed surface of grains containing this solution.

  10. Evaluation of the Chromium Resonance Parameters Including Resonance Parameter Covariance

    SciTech Connect

    Leal, Luiz C; Derrien, Herve; Guber, Klaus H; Arbanas, Goran; Wiarda, Dorothea

    2011-01-01

    The intent of this work is to report the results and describe the procedures utilized to evaluate the chromium isotopes' cross sections, i.e., (50)Cr, (52)Cr, (53)Cr, and (54)Cr, for criticality safety applications. The evaluations were done in the resolved resonance region using the reduced Reich-Moore R-matrix formalism. The novel aspect of this evaluation is the inclusion of new transmission and capture cross-section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) for energies below 100 keV and the extension of the (53)Cr energy region. The resonance analysis was performed with the multilevel R-matrix code, SAMMY, which utilizes the generalized least-squares technique based on the Bayes' theory. Complete sets of resonance parameters and resonance parameter covariance matrices (RPCMs) were obtained for each of the chromium isotopes from the SAMMY analysis of the experimental database.

  11. [Poisoning by chromium and its long lasting detoxication].

    PubMed

    Ryselis, Stanislovas; Abdrachmanovas, Olegas; Vitkuviene, Birute; Naginiene, Rima

    2002-01-01

    Long lasting influence of cumulated Cr provide irreversible damages of vascular walls, organs and their systems. During long lasting treatment most of Cr is removed during the first 20 days through bileric tract and at the same time through the renal tract the Cr amounts decreases because chromium-d-penicilamin complex in hepatocytes induces synthesis of specific chromium-d-penicilamin binding labile protein and they are removed with bile. The levels of essential microelements (Cu and Zn) are maintained at the level of the physiological tolerance during treatment. Cr removes very slowly (about a year) from human body, and after treatment patients health do not improve because Cr-inducted damages of vascullars, organs and their systems are not recovered. The treatment must be evaluated continuously by controlling concentrations' of Cr, Cu, Zn and other microelements in the blood, plasma and urine by electrothermal atomic absorbtion spectrophotometry methods.

  12. Adsorption of hexavalent chromium onto sisal pulp/polypyrrole composites

    NASA Astrophysics Data System (ADS)

    Tan, Y. Y.; Wei, C.; Gong, Y. Y.; Du, L. L.

    2017-02-01

    Sisal pulp/polypyrrole composites(SP/PPy) utilized for the removal of hexavalent chromium [Cr(VI)] from wastewater, were prepared via in-situ chemical oxidation polymerization approach. The structure and morphology of the SP/PPy were analyzed by polarizing optical microscopy (POM), field-emission scanning electron microscopy (SEM)), Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the results indicated SP could be efficient dispersion of PPy. The hexavalent chromium adsorption results indicate adsorption capacity of the SP/PPy were dependent on the initial pH, with an optimum pH of 2.0. The sorption kinetic data fitted well to the pseudo-second order model and isotherm data fitted well to the Langmuir isotherm model. The maximum adsorption capacity determined from the Langmuir isotherm is 336.70 mg/g at 25° C.

  13. Chromium-based catalyst for HFC-125 synthesis: promoters effect

    NASA Astrophysics Data System (ADS)

    Reshetnikov, S. I.; Simonova, L. G.; Zirka, A. A.; Petrov, R. V.

    2016-01-01

    A variation of promoters, including rare-earth elements, allows to control of the specific surface and, perhaps, oxidation state of chromium and, consequently, catalyst activity and selectivity of chromium-based catalyst for HFC-125. To improve the catalytic properties of the 15% Cr2O3 γ - 85% -Al2O3 oxide system were added promoters (Ni or Cu or Co) in an amount of 5 wt% in terms of oxides. It was found that additional promotion Cr-Al samples by nickel and copper allow to increase the specific surface area of about 25-40% and the activity increased about 2 times. Modification of cobalt resulted in a decrease of the surface by 20% and the activity decreased by about 2 times.

  14. Method for heat treating iron-nickel-chromium alloy

    DOEpatents

    Not Available

    1980-04-03

    A method is described for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a morphology of the gamma-double prime phase enveloping the gamma-prime, the alloy consisting essentially of about 25 to 45% nickel, 10 to 16% chromium, 1.5 to 3% of an element selected from the group consisting of molybdenum and niobium, about 2% titanium, about 3% aluminum, and the remainder substantially all iron. To obtain optimum results, the alloy is heated to a temperature of 1025 to 1075/sup 0/C for 2 to 5 minutes, cold-worked about 20 to 60%, aged at a temperature of about 775/sup 0/C for 8 hours followed by an air-cool, and then heated to a temperature in the range of 650 to 700/sup 0/C for 2 hours followed by an air-cool.

  15. A mathematical model for the iron/chromium redox battery

    NASA Technical Reports Server (NTRS)

    Fedkiw, P. S.; Watts, R. W.

    1984-01-01

    A mathematical model has been developed to describe the isothermal operation of a single anode-separator-cathode unit cell in a redox-flow battery and has been applied to the NASA iron/chromium system. The model, based on porous electrode theory, incorporates redox kinetics, mass transfer, and ohmic effects as well as the parasitic hydrogen reaction which occurs in the chromium electrode. A numerical parameter study was carried out to predict cell performance to aid in the rational design, scale-up, and operation of the flow battery. The calculations demonstrate: (1) an optimum electrode thickness and electrolyte flow rate exist; (2) the amount of hydrogen evolved and, hence, cycle faradaic efficiency, can be affected by cell geometry, flow rate, and charging procedure; (3) countercurrent flow results in enhanced cell performance over cocurrent flow; and (4) elevated temperature operation enhances cell performance.

  16. Method for heat treating iron-nickel-chromium alloy

    DOEpatents

    Korenko, Michael K.

    1980-01-01

    A method for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a morphology of the gamma-double prime phase enveloping the gamma-prime phase, the alloy consisting essentially of about 40 to 50% nickel, 7.5 to 14% chromium, 1.5 to 4% niobium, 0.3 to 0.75% silicon, 1 to 3% titanium, 0.1 to 0.5% aluminum, 0.02 to 1% carbon, 0.002 to 0.0015% boron and the remain substantially all iron. To obtain optimal results, the alloy is cold-worked 20 to 60% followed by heating at 1050.degree. C. for 1/2 hour with an air-cool plus heating at 800.degree. C. for 2 hours with a furnace cool to 625.degree. C. The alloy is then held at 625.degree. C. for 12 hours, followed by an air-cool.

  17. Method for heat treating iron-nickel-chromium alloy

    DOEpatents

    Merrick, Howard F.; Korenko, Michael K.

    1982-01-01

    A method for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a bimodal distribution of gamma prime phase within a network of dislocations, the alloy consisting essentially of about 25% to 45% nickel, 10% to 16% chromium, 1.5% to 3% of an element selected from the group consisting of molybdenum and niobium, about 2% titanium, about 3% aluminum, and the remainder substantially all iron. To obtain optimum results, the alloy is heated to a temperature of 1025.degree. C. to 1075.degree. C. for 2-5 minutes, cold-worked about 20% to 60%, aged at a temperature of about 775.degree. C. for 8 hours followed by an air-cool, and then heated to a temperature in the range of 650.degree. C. to 700.degree. C. for 2 hours followed by an air-cool.

  18. Adsorption of chromium onto activated alumina: kinetics and thermodynamics studies.

    PubMed

    Marzouk, Ikhlass; Dammak, Lassaad; Hamrouni, Béchir

    2013-02-01

    In this study, the removal of chromium (VI) by adsorption on activated alumina was investigated and the results were fitted to Langmuir, Freundlich, Dubinin-Redushkevich, and Temkin adsorption models at various temperatures. The constants of each model were evaluated depending on temperature. Thermodynamic parameters for the adsorption system were determined at 10, 25 and 40 degrees C. (deltaH degrees = -21.18 kJ x mol(-1); deltaG degrees = -8.75 to -7.43 kJ x mol(-1) and deltaS degrees = -0.043 kJ x K(-1) x mol(-1)). The obtained values showed that chromium (VI) adsorption is a spontaneous and exothermic process. The kinetic process was evaluated by first-order, second-order and Elovich kinetic models.

  19. Chromium (VI) purification using pine sawdust in batch systems

    NASA Astrophysics Data System (ADS)

    Politi, Dorothea; Sidiras, Dimitris

    2012-12-01

    Pine sawdust, a waste generated in furniture industry, has been used as low-cost potential adsorbent. This low-cost adsorbent was used for the removal of chromium (VI) from an aqueous solution. The kinetics of adsorption and extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbent and adsorbate. The effect of hydrogen ion concentration, contact time, adsorbent dose and initial concentration of adsorbate on the uptake of chromium were studied in batch experiments. The adsorption data has been correlated with Lagergren - Eldridge pseudofirst order kinetic model. The efficiency of adsorbent material for the removal of Cr(VI) was found to be between 13.1 and 95.6%, respectively. These results depend on the conditions of pH, contact time, sawdust dose and Cr(VI) concentration.

  20. X-616 Chromium Sludge Lagoons pictorial overview, Piketon, Ohio. Environmental Restoration Program

    SciTech Connect

    Not Available

    1992-10-01

    The Portsmouth Gaseous Diffusion Plant uses large quantities of water for process cooling. The X-616 Liquid Effluent Control Facility was placed in operation in December 1976 to treat recirculation cooling water blowdown from the process cooling system. A chromium-based corrosion inhibitor was used in the cooling water system. A chromium sludge was produced in a clarifier to control chromium levels in the water. Chromium sludge produced by this process was stored in two surface impoundments called the X-616 Chromium Sludge Lagoons. The sludge was toxic due to its chromium concentration and therefore required treatment. The sludge was treated, turning it into a sanitary waste, and buried in an Ohio EPA approved landfill. The plant`s process cooling water system has changed to a more environmentally acceptable phosphate-based inhibitor. Closure activities at X-616 began in August 1990, with all construction activities completed in June 1991, at a total cost of $8.0 million.

  1. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    SciTech Connect

    Oyaidzu, M.; Isobe, K.; Hayashi, T.

    2015-03-15

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions.

  2. Role of heteroatoms in activated carbon for removal of hexavalent chromium from wastewaters.

    PubMed

    Valix, M; Cheung, W H; Zhang, K

    2006-07-31

    Heteroatoms are elements including sulfur, nitrogen, oxygen and hydrogen which are found on the surface of activated carbons. This study investigated the surface modification arising from heteroatoms bonding to carbon aromatic rings within the activated carbon and their corresponding influence on the chromium adsorption process. Activated carbons were prepared from bagasse by physical. Chromium removal capacities of these activated carbons by adsorption and reduction were determined. Models which related the chromium adsorption and reduction capacities of activated carbons to carbon acidity and heteroatom site concentrations were established using multi-variable linear regression method. It was found the individual heteroatoms contributed separately to the basicity of the carbon which in turn determined the mechanism by which chromium was removed from solution. The surface areas of the carbons were also observed to influence the adsorption and reduction of chromium. These understandings provide the fundamental method of optimising chromium removal through suitable control of carbon surface chemistry and textural properties.

  3. Dietary chromium supplementation for targeted treatment of diabetes patients with comorbid depression and binge eating.

    PubMed

    Brownley, Kimberly A; Boettiger, Charlotte A; Young, Laura; Cefalu, William T

    2015-07-01

    Dietary chromium supplementation for the treatment of diabetes remains controversial. The prevailing view that chromium supplementation for glucose regulation is unjustified has been based upon prior studies showing mixed, modest-sized effects in patients with type 2 diabetes (T2DM). Based on chromium's potential to improve insulin, dopamine, and serotonin function, we hypothesize that chromium has a greater glucoregulatory effect in individuals who have concurrent disturbances in dopamine and serotonin function--that is, complex patients with comorbid diabetes, depression, and binge eating. We propose, as suggested by the collective data to date, the need to go beyond the "one size fits all" approach to chromium supplementation and put forth a series of experiments designed to link physiological and neurobehavioral processes in the chromium response phenotype.

  4. Development of the revised drinking water standard for chromium.

    PubMed

    Goldhaber, S; Vogt, C

    1989-10-01

    Comprehensive regulations are being developed to limit human exposure to contamination in drinking water by the United States Environmental Protection Agency (EPA) under the authority of the Safe Drinking Water Act (SDWA). These regulations are being developed in several phases and include synthetic organic chemicals, inorganic chemicals, microbiological contaminants and radionuclides. This paper addresses the fundamental concepts and approaches used by EPA in setting drinking water regulations and how EPA is using these concepts to revise the drinking water standard for chromium.

  5. Partitioning of chromium between silicate crystals and melts

    NASA Technical Reports Server (NTRS)

    Huebner, J. S.; Lipin, B. R.; Wiggins, L. B.

    1976-01-01

    Experiments were performed determining the distribution of chromium between olivine, pyroxenes, and melt at oxygen fugacity values near those of lunar rocks for a wide range of bulk compositions. The range of values of D-Cr (wt% of Cr2O3 in crystals/Cr2O3 in melt) is 0.6-1.3 for olivine and 1.6-3.5 for pyroxene; this ratio shows no obvious dependence on any experimental parameter.

  6. A newly developed chromium(III) gel technology

    SciTech Connect

    Sydansk, R.D. . Research Div.)

    1990-08-01

    Laboratory testing of a recently developed chromium(III) (Cr(III)) gel technology is reported. The gels can be used in conjunction with a number of oilfield treatments. The single-fluid acrylamide-polymer/Cr(III)-carboxylate aqueous gels are formed by crosslinking acrylamide polymer with a Cr(III)-carboxylate-complex crosslinking agent. Representative gel compositions and associated gel properties are discussed.

  7. Electrodeposition of Chromium with Periodic Reverse and Pulsed Current

    DTIC Science & Technology

    1976-04-01

    backs of specimens 8 Current density tests 9 Reverse current levels 10 Additives in the chromium bath 12 Oxalic acid 12 Boric acid 14 Sodium...bath for PR 35 plating Boric acid added to 100 and 250 g/1 Cr03 bath 35 (308-9) Addition of 50 g/1 boric acid with and without 36 PR 120...improved de- posit distribution both with and without PR. Additives tried with some success included oxalic acid , boric acid and sodium hydroxide. The

  8. Spectroscopic characteristics of chromium doped mullite glass-ceramics

    SciTech Connect

    Wojtowicz, A.J.; Meng, W.; Lempicki, A.; Beall, G.H.; Hall, D.W.; Chin, T.C.

    1988-06-01

    Characteristics of chromium doped mullite ceramics are discussed with reference to possible laser applications. Dominant features are attributed to large and inherent spectroscopic inhomogeneity of mullite. The spectroscopic data are analyzed using a generalized McCumber theory. The peak stimulated emission cross section is 0.54 x 10/sup -20/ cm/sup 2/. This, together with preliminary single-pass measurements, indicate that gain for mullite is about 2.6 times smaller than gain for alexandrite.

  9. Chromium cycling in soils and water: links, gaps, and methods.

    PubMed Central

    Bartlett, R J

    1991-01-01

    The major links in the cycling of chromium in soils and in natural waters are between chromium(III) and chromium (VI). Between the larger links are lesser links involving processes of mobilization and oxidation of CrIII and reduction of CrVI. The gaps are mainly in our understanding of the factors that control these processes. If soluble CrIII is added to an "average" soil, a portion of it will become immediately oxidized by manganese oxides to CrVI. The rest of the CrIII may remain reduced for long periods of time, even in the presence of electron-accepting manganese oxides. However, this less available CrIII can be mobilized by low molecular weight organic complexers and then oxidized where redox conditions are optimal. Usually part of any CrVI added to a soil or sediment will be reduced instantly, especially under acid conditions. On the other hand, high concentrations of polluting CrVI may quickly exhaust the readily available reducing power of the matrix material and excess CrVI, the thermodynamically stable form in air, may persist for years in soils or lagoons without reduction. Cleanup of chromium pollution must involve the surrounding of both CrIII and CrVI with excesses of slowly available reducing substances and sealing them permanently from inputs of atmospheric oxygen. Monitoring the effectiveness of the measures is mandatory, but fortunately the chemical testing for CrVI in soil and water is simple and problem free compared with most colorimetric determinations. PMID:1935847

  10. Diffusion and leachability index studies on stabilization of chromium contaminated soil using fly ash.

    PubMed

    Kanchinadham, Sri Bala Kameswari; Narasimman, L M; Pedaballe, Vihita; Kalyanaraman, Chitra

    2015-10-30

    Experiments were performed to establish a feasible treatment process for the solidification and stabilization (S/S) of soil contaminated by leaching of Cr(VI) from Chromite ore processing residue (COPR). Reduction of the highly mobile Cr(VI) was performed using calcium polysulfide (CaS5) with a dosage of 3 times the molar stoichiometric ratio for the initial concentration of Cr(VI) present in the chromium contaminated soil (CCS). The CCS was solidified and stabilized (S/S) using fly ash (FA) in various proportions i.e., 1:1, 1:2, 1:3 (FA: CCS) with and without using reducing agent i.e., CaS5. Leachability tests such as Toxicity Characteristic Leaching Procedure (TCLP) and semi-dynamic long term leachability tests indicated that the CaS5 was effective in reduction of Cr(VI) followed by the S/S process. Leachability Index was derived from the results of the semi-dynamic long term leachability tests and was between 8 and 9, indicating that FA is an effective treatment for disposal into secured landfills for CCS. The characteristic compressive strength of the CaS5 treated CCS with FA mortar blocks were between 24.47 and 40.49 kg/cm(2). Considering the cost of CaS5 and FA, a total expenditure of Rs. 7826 i.e., US $ 130.4 would be required for remediation of one tonne of CCS.

  11. Reduction of hexavalent chromium by a novel Ochrobactrum sp. - microbial characteristics and reduction kinetics.

    PubMed

    Narayani, M; Vidya Shetty, K

    2014-04-01

    A Gram negative hexavalent chromium (Cr(VI)) reducing bacteria, Ochrobactrum sp. Cr-B4 (genbank accession number: JF824998) was isolated from the aerator water of an activated sludge process of a wastewater treatment facility of a dye and pigment based specialty chemical industry. It showed a resistance for 1000 mg L(-1) Cr(VI). It exhibited resistance against other heavy metal ions like Ni(2+) (900 mg L(-1) ), Cu(2+) (500 mg L(-1) ), Pb(2+) (800 mg L(-1) ), and Cd(2+) (250 mg L(-1) ), Zn(2+) (700 mg L(-1) ), Fe(3+) (800 mg L(-1) ), and against selected antibiotics. Cr-B4 could efficiently reduce 200 mg L(-1) Cr(VI) completely in nutrient and LB media and could convert Cr(VI) to Cr(III) efficiently. Cr(VI) reduction in nutrient media followed allosteric enzyme kinetics with Km values of 59.39 mg L(-1) and Vmax values of 47.03 mg L(-1)  h(-1) . The reduction in LB media followed Michaelis-Menten kinetics with Km values of 99.52 mg L(-1) and Vmax of 77.63 mg L(-1)  h(-1) . Scanning electron micrograms revealed the presence of extracellular polymeric secretions.

  12. Urinary chromium excretion in response to an insulin challenge is not a biomarker for chromium status.

    PubMed

    Love, Sharifa T; Di Bona, Kristin R; Sinha, Sarmistha Halder; McAdory, DeAna; Skinner, Brittany R; Rasco, Jane F; Vincent, John B

    2013-04-01

    Over 50 years ago, chromium (Cr) was proposed to be an essential trace element; however, recent studies indicate that this status should be removed as the effects of Cr supplementation appear to be pharmacological rather than nutritional. The pharmacological basis for Cr's effects can explain the inability of investigators to discover a biomarker for Cr status. One potential biomarker has not been examined to date. Cr is known to be mobilized in the body in response to insulin (or insulin release in response to a glucose challenge), resulting in an increase in urinary Cr excretion. The magnitude of increase in urinary Cr loss as a function of dietary Cr intake was tested as a potential biomarker for Cr. Zucker lean rats housed in carefully controlled metal-free conditions were provided a series of purified diets containing variable Cr contents (from 16 μg/kg diet to 2,000 μg/kg) for 23 weeks. The 16 μg/kg diet contained less Cr than any diet examined to date. Urine samples were collected before and after insulin and glucose challenges (0, 2, 6, and 12 h postinjection). Urinary Cr levels were analyzed by the standard method of addition using graphite furnace atomic absorption. The rate of urinary Cr loss after a glucose or insulin challenge was found to not be dependent on the Cr content of the rats' diets. Blood iron levels of the rats were also measured to determine if the addition of Cr to the diet altered iron status. The Cr content of the diet was found to have no affect on blood iron levels. Overall, the study demonstrated that insulin-stimulated urinary Cr excretion cannot be used as a biomarker for Cr status.

  13. Chromium(III) and chromium(VI) release from leather during 8 months of simulated use

    PubMed Central

    Lidén, Carola

    2016-01-01

    Summary Background Chromium (Cr) release from Cr‐tanned leather articles is a major cause of Cr contact dermatitis. It has been suggested that Cr(VI) release from leather is not necessarily an intrinsic property of the leather, but is strongly dependent on environmental conditions. Objectives To test this hypothesis for long‐term (8 months) simulated use. Materials and methods The release of total Cr and Cr(VI) from Cr‐tanned, unfinished leather was analysed in subsequent phosphate buffer (pH 8.0) immersions for a period of 7.5 months. The effect of combined ultraviolet treatment and alkaline solution (pH 12.1) was tested. Dry storage [20% relative humidity (RH)] was maintained between immersions. Atomic absorption spectroscopy, X‐ray fluorescence and diphenylcarbazide tests were used. Results Cr(VI) release was dependent on previous dry storage or alkaline treatment, but not on duration or number of previous immersions. Cr(III) release decreased with time. Fifty‐two percent of the total Cr released during the last immersion period was Cr(VI). Cr(VI) release exceeded 9 mg/kg in all immersion periods except in the first 10‐day immersion (2.6 mg/kg). Conclusions Cr(VI) release is primarily determined by environmental factors (RH prior to immersion, solution pH, and antioxidant content). The RH should be kept low prior to testing Cr(VI) release from leather. PMID:27144948

  14. Achieving Zero Stress in Iridium, Chromium, and Nickle Thin Films

    NASA Technical Reports Server (NTRS)

    Broadway, David M.; Weimer, Jeffrey; Gurgew, Danielle; Lis, Tomasz; Ramsey, Brian D.; O'Dell, Stephen L.; Ames, A.; Bruni, R.

    2015-01-01

    We examine a method for achieving zero intrinsic stress in thin films of iridium, chromium, and nickel deposited by magnetron sputter deposition. The examination of the stress in these materials is motivated by efforts to advance the optical performance of light-weight x-ray space telescopes into the regime of sub-arc second resolution that rely on control of the film stress to values within 10-100 MPa. A characteristic feature of the intrinsic stress behavior in chromium and nickel is their sensitivity to the magnitude and sign of the intrinsic stress with argon gas pressure, including the existence of a critical pressure that results in zero film stress. This critical pressure scales linearly with the film's density. While the effect of stress reversal with argon pressure has been previously reported by Hoffman and others for nickel and chromium, we have discovered a similar behavior for iridium. Additionally, we have identified zero stress in iridium shortly after island coalescence. This feature of film growth is used for achieving a total internal stress of -2.89 MPa for a 15.8 nm thick iridium film. The surface roughness of this low-stress film was examined using scanning probe microscopy (SPM) and x-ray reflectivity (XRR) at CuKa and these results presented and discussed.

  15. Eolian transport of geogenic hexavalent chromium to ground water

    USGS Publications Warehouse

    Wood, W.W.; Clark, D.; Imes, J.L.; Councell, T.B.

    2010-01-01

    A conceptual model of eolian transport is proposed to address the widely distributed, high concentrations of hexavalent chromium (Cr+6) observed in ground water in the Emirate of Abu Dhabi, United Arab Emirates. Concentrations (30 to more than 1000 μg/L Cr+6) extend over thousands of square kilometers of ground water systems. It is hypothesized that the Cr is derived from weathering of chromium-rich pyroxenes and olivines present in ophiolite sequence of the adjacent Oman (Hajar) Mountains. Cr+3 in the minerals is oxidized to Cr+6 by reduction of manganese and is subsequently sorbed on iron and manganese oxide coatings of particles. When the surfaces of these particles are abraded in this arid environment, they release fine, micrometer-sized, coated particles that are easily transported over large distances by wind and subsequently deposited on the surface. During ground water recharge events, the readily soluble Cr+6 is mobilized by rain water and transported by advective flow into the underlying aquifer. Chromium analyses of ground water, rain, dust, and surface (soil) deposits are consistent with this model, as are electron probe analyses of clasts derived from the eroding Oman ophiolite sequence. Ground water recharge flux is proposed to exercise some control over Cr+6 concentration in the aquifer.

  16. Fabrication of Carbon Nanotube - Chromium Carbide Composite Through Laser Sintering

    NASA Astrophysics Data System (ADS)

    Liu, Ze; Gao, Yibo; Liang, Fei; Wu, Benxin; Gou, Jihua; Detrois, Martin; Tin, Sammy; Yin, Ming; Nash, Philip; Tang, Xiaoduan; Wang, Xinwei

    2016-03-01

    Ceramics often have high hardness and strength, and good wear and corrosion resistance, and hence have many important applications, which, however, are often limited by their poor fracture toughness. Carbon nanotubes (CNTs) may enhance ceramic fracture toughness, but hot pressing (which is one typical approach of fabricating CNT-ceramic composites) is difficult to apply for applications that require localized heat input, such as fabricating composites as surface coatings. Laser beam may realize localized material sintering with little thermal effect on the surrounding regions. However, for the typical ceramics for hard coating applications (as listed in Ref.[1]), previous work on laser sintering of CNT-ceramic composites with mechanical property characterizations has been very limited. In this paper, research work has been reported on the fabrication and characterization of CNT-ceramic composites through laser sintering of mixtures of CNTs and chromium carbide powders. Under the studied conditions, it has been found that laser-sintered composites have a much higher hardness than that for plasma-sprayed composites reported in the literature. It has also been found that the composites obtained by laser sintering of CNTs and chromium carbide powder mixtures have a fracture toughness that is ~23 % higher than the material obtained by laser sintering of chromium carbide powders without CNTs.

  17. Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

    PubMed Central

    Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

    2014-01-01

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan; cooking times of 2 to 20 hours, ten consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After six hours of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34 fold and Cr increased approximately 35 fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, though significant metal contributions to foods were still observed. The tenth cooking cycle, resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage. PMID:23984718

  18. Magnetically active biosorbent for chromium species removal from aqueous media.

    PubMed

    Abdel-Fattah, Tarek M; Mahmoud, Mohamed E; Osmam, Maher M; Ahmed, Somia B

    2014-01-01

    A magnetically active composite as adsorbent was synthesized via a facile in situ one-pot impregnation of magnetic nano-iron oxide (Fe₃O₄) on the surface of activated carbon (AC) for the formation of AC-Fe₃O₄. Baker(')s yeast was physically loaded on the resultant adsorbent AC-Fe₃O₄ to form a novel yeast coated magnetic composite AC-Fe₃O₄-Yst as biosorbent. The two synthesized adsorbents were characterized by using a scanning electron microscope (SEM) and assessed using Langmuir, the Brunauer-Emmet-Teller (BET) and Dubinin-Radushkevich (D-R) isotherm models. The validity and applicability of these two sorbents in adsorptive removal of chromium species, Cr(VI) and Cr(III), from aqueous solutions under the effect of a magnetic field were studied and evaluated in the presence of various controlling parameters in order to identify the optimal pH, contact time, mass dose and chromium concentrations for such adsorption process. Also, single and multi-stage micro-column techniques were used to study the potential applications of AC-Fe₃O₄ as magnetically active adsorbents and AC-Fe₃O₄-Yst as magnetically active biosorbents, for the removal of chromium species from various real water samples.

  19. Toxicity and accumulation of chromium in Ceratophyllum demersum L

    SciTech Connect

    Garg, P.; Chandra, P. )

    1990-03-01

    As a result of heavy metal pollution, significant degradation in water quality has occurred leading to acute scarcity of safe drinking water. Efforts have recently been made to develop simple but reliable biological systems to upgrade the water quality. In this process several aquatic plants effective in heavy metal uptake were identified. Recently, a few aquatic species have been reported to accumulate chromium. However, not much information is available on Cr uptake by the aquatic vascular plants. Chromium, which is one of the highly toxic metals is being released to the water bodies in high concentrations through the effluents from industries like leather, dye, paint, ink, electroplating and paper. The interest on C. demersum a submerged aquatic plant was aroused because of its common occurrence and luxuriant growth in a polluted water body which contained 0.05 to 0.22 ppm Cr. Plants analyzed from this site also showed high accumulation of Cr. In view of this it was considered worthwhile to evaluate chromium uptake ability of this plant under the laboratory conditions.

  20. Changes in oxidation state of chromium during LDEF exposure

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1992-01-01

    The solar collector used for the McDonnell-Douglas Cascade Variable Heat Pipe, Experiment A0076 (Michael Grote - Principal Investigator) was finished with black chromium plating as a thermal control coating. The coating is metallic for low emittance, and is finely microcrystalline to a dimension which yields its high absorptivity. An underplate of nickel was applied to the aluminum absorber plate in order to achieve optimal absorptance characteristics from the black chromium plate surface. Experiment A0076 was located at tray position F9, receiving a projected 8.7 x 10 exp 21 atomic oxygen atoms/sq cm and 11,200 ESH solar radiation. During retrieval, it was observed that the aluminized kapton thermal blankets covering most of the tray were severely eroded by atomic oxygen, and that a 'flap' of aluminum foil was overlaying a roughly triangular shaped portion of the absorber panel. The aluminum foil 'flap' was lost sometime between the Long Duration Exposure Facility (LDEF) retrieval and deintegration. At deintegration, the black chromium was observed to have discolored where it had been covered by the foil 'flap'. A summary of the investigation into the cause of the discoloration is presented.

  1. Structural and magnetic properties of chromium doped zinc ferrite

    SciTech Connect

    Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena; Mohammed, E. M.; Joseph, Shaji

    2014-01-28

    Zinc chromium ferrites with chemical formula ZnCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  2. Ultrafast Dynamics near the M-edge in Chromium

    NASA Astrophysics Data System (ADS)

    McFarland, Brian; Zhu, Jian-Xin; Prasankumar, Rohit; Rodriguez, George; Sandberg, Richard; Taylor, Antoinette; Yarotski, Dmitry

    2015-03-01

    The exploration of element specific ultrafast spin dynamics in transition metals has been extended by recent advances in table top VUV sources based on high harmonic generation. These sources provide femtosecond time resolution at photon energies that span the magnetism sensitive 3p to 3d band absorption (M-edge) in these materials. The time scale of spin dynamics determines the fundamental limits of magnetic data recording and gives insight into magnetoelectric coupling mechanisms in complex functional materials. Though there have been multiple time-resolved studies on ferromagnetic systems, antiferromagnetic (AFM) dynamics remains largely unexplored. As an AFM test system we choose chromium and measure transient reflectivity for photon energies spanning the chromium M-edge. Picosecond dynamics are measured throughout the spectrum of the VUV probe beam after excitation by an IR laser pulse. A dramatic difference is observed in the transient magnetic linear absorption dichroism of chromium for photon energies above and below the M-edge (~ 46 eV) as temperature is varied through the AFM transition. While a decrease in reflectivity is seen below the M-edge we find an increase in reflectivity above the edge. We attribute this variation to interplay between electronic and magnetic responses and discuss its relation to ultrafast magnetic ordering dynamics.

  3. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    NASA Astrophysics Data System (ADS)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  4. Bioremediation of hexavalent chromium by a cyanobacterial mat

    NASA Astrophysics Data System (ADS)

    Shukla, Dhara; Vankar, Padma S.; Srivastava, Sarvesh Kumar

    2012-12-01

    The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2-10, 15-30 and 300 ppm at pH 5.5-6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform-infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5-6.2.

  5. Stainless steel leaches nickel and chromium into foods during cooking.

    PubMed

    Kamerud, Kristin L; Hobbie, Kevin A; Anderson, Kim A

    2013-10-02

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan, cooking times of 2-20 h, 10 consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After 6 h of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold, respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34-fold and Cr increased approximately 35-fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, although significant metal contributions to foods were still observed. The tenth cooking cycle resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage.

  6. Chromium and manganese interactions in streptozocin-diabetic rats

    SciTech Connect

    Davis, M.L.; Jarrett, C.R.; Adeleye, B.O.; Stoecker, B.J. )

    1991-03-15

    Weanling male rats were fed casein-based diets low in chromium and manganese ({minus}Cr-MN) or supplemented with 1 ppm chromium as chromium chloride (+Cr) and/or 55 ppm manganese as manganous carbonate in a factorial design. After 7 weeks on the experimental diets, half of the rats in each group were injected on 2 consecutive days with 55 mg/kg streptozocin (STZ) in citrate buffer pH 4. Four weeks after injection, serum glucose in the diabetic group supplement with both Cr and Mn was not different from non-diabetic animals; however, diabetic animals in {minus}Cr groups or in the +Cr-Mn group had significantly elevated serum glucose. Serum insulin was reduced by STZ. A significant interaction between Mn and diabetes affected serum cortisol concentrations. More new tissue was formed on a polyvinyl sponge inserted under the skin in +Mn animals. In this study, the STZ animals were more sensitive than the control animals to dietary Cr and Mn concentrations.

  7. Effects of chromic-acid concentration on the structure and properties of chromium coatings

    SciTech Connect

    Solodkova, L.N.; Solov'eva, Z.A.; Monev, M.; Nikolova, S.; Rashkov, S.; Dobrev, Ts.

    1987-10-01

    In the interest of decreasing the amount of chromium and other electrolytic effluents that enter the waste stream during chromium electrodeposition processes, and of optimizing plating speeds at reduced chromic acid concentrations, the authors seek to establish the effects of decreasing the chromic acid concentration in the electrolyte on the microstructure, microhardness, internal stress behavior, and tendency toward hydridation of chromium coatings obtained from various electrolyte compositions. Plating kinetics and lattice parameters were also investigated.

  8. Ameliorating effect of chromium administration on hepatic glucose metabolism in streptozotocin-induced experimental diabetes.

    PubMed

    Sundaram, Bhuvaneshwari; Singhal, Kirti; Sandhir, Rajat

    2012-01-01

    Chromium has been recognized as an essential trace element that plays an important role in carbohydrate metabolism. However, the molecular mechanisms involved in its action are not clear. This study was undertaken to understand the mechanism of chromium action in experimental diabetes. Streptozotocin-induced diabetic animals were administered chromium as chromium picolinate (CrP) at a daily dose of 1 mg/kg body weight for a period of 4 weeks. It was observed that chromium complexed with picolinate was effective in lowering plasma glucose levels as well as was able to alleviate polyphagia, polydipsia, and weight loss in diabetic animals. Administration of chromium was also found to normalize glycogen content in liver of diabetic animals to near control levels. The reduction in plasma glucose levels by chromium was accompanied by increase in activity of glycolytic enzymes (e.g., glucokinase, phosphofructokinase, and pyruvate kinase) and by suppression in activity of gluconeogenic enzymes (e.g., glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) in liver. Hepatic glucose uptake was found to be increased by chromium supplementation as demonstrated by decrease in Km and increase in Vmax values in diabetic animals. Chromium levels were lower in the liver of diabetic rats when compared with that of control rats. A negative correlation was observed between plasma glucose and chromium concentration in patients with diabetes. The data suggests that chromium supplementation as CrP is beneficial in correcting hyperglycemia, implying that the modulation of the glucose metabolism by chromium may be therapeutically beneficial in the treatment of diabetes.

  9. Simultaneous determination of chromium, cadmium, and lead and evaluation of the correlation between chromium and cotinine in Chinese smokers.

    PubMed

    Tian, Yongfeng; Hou, Hongwei; Zhu, Fengpeng; Wang, An; Liu, Yong; Hu, Qingyuan

    2014-04-01

    Heavy metals in tobacco caused wide public concern. To study the impact of heavy metals in smokers, 193 smokers and 58 nonsmokers were surveyed, and their urinary levels of chromium (UCr), lead (UPb), and cadmium (UCd) were assayed. In this study, UCr, UPb, and UCd in smokers (33.41 ± 14.99, 3.21 ± 1.34, 0.38 ± 0.64 μg/24 h, respectively) and nonsmokers (27.45 ± 10.49, 3.02 ± 0.88, 0.20 ± 0.16 μg/24 h, respectively) were determined by inductively coupled plasma mass spectrometry. The results showed that the content of UCr, UPb, and UCd in smokers were higher than in nonsmokers. Further analyses of correlations between the levels of urinary chromium and cotinine revealed positive relationship (correlation coefficient r = 0.51).

  10. Republic P-47C Thunderbolt

    NASA Technical Reports Server (NTRS)

    1943-01-01

    Republic P-47C Thunderbolt: Republic's P-47 was one example of a perfect marriage of airframe and power plant. The engine of this P-47C was still under study, as can ascertained by the survey rake for measuring propeller thrust. This rake protrudes from the fuselage just behind the cowling ahead and in front of the wing.

  11. Republic P-47C Thunderbolt

    NASA Technical Reports Server (NTRS)

    1943-01-01

    Republic P-47C Thunderbolt: Republic's P-47 was one example of a perfect marriage of airframe and power plant. The engine of this P-47C was still under study, as can be ascertained by the survey rake for measuring propeller thrust. This rake protrudes from the fuselage just behind the cowling ahead and in front of the wing.

  12. Republic P-47B Thunderbolt

    NASA Technical Reports Server (NTRS)

    1942-01-01

    Republic P-47B Thunderbolt: The Republic P-47B Thunderbolt was one of the great fighters used by the U. S. Army Air Force in World War II, and crews praised its ability to absorb punishment. This P-47B was used by NACA engineers to study the horizontal tail loads experienced by a fighter during abrupt maneuvers.

  13. The regeneration and recycle of chromium etching solutions using concentrator cell membrane technology.

    PubMed

    Chaudhary, Abdul J; Ganguli, Bijita; Grimes, Susan M

    2006-02-01

    The regeneration of chromium (VI) and the recovery of etched copper from chromium etching solutions by electrodialysis is improved by the addition of a concentrator cell in the catholyte chamber. The concentrator media used are ion-exchange resins or activated carbon cloth. The maximum percentages for the regeneration of chromium and recovery of copper in these systems is however less than 80% and 90% respectively because of the competition between the processes of oxidation of Cr(III) and electrodeposition of copper. A novel combination of electrolysis with electrodialysis and concentrator cell technology is developed that achieves 92% chromium regeneration and 90% copper recovery.

  14. The determination of nanogram amounts of Chromium in urine by x-ray fluorescence spectroscopy

    USGS Publications Warehouse

    Beyermann, K.; Rose, H.J.; Christian, R.P.

    1969-01-01

    Nanogram amounts of chromium can be extracted as oxinate into chloform. By treatment of the chloroform layer 3 M hydrochloric acid, oxinates of other elements and excess of reagent are removed, leaving a chloroform solution of the chromium chelate only. This solution is concentrated and transferred to the top of a small brass rod acting as sample holder. The intensity of the X-ray fluorescence of the Cr K?? line is measured with curved crystal optics. Chromium amounts greater than 5 ng can be detected. The application of the procedure to the analysis of the chromium content of urine is demonstrated. ?? 1969.

  15. Assessing the impact of geogenic chromium uptake by carrots (Daucus carota) grown in Asopos river basin.

    PubMed

    Lilli, Maria A; Syranidou, Evdokia; Palliou, Andriana; Nikolaidis, Nikolaos P; Karatzas, George; Kalogerakis, Nicolas

    2017-01-01

    A methodology was developed to assess the impact of geogenic origin hexavalent chromium uptake by carrots, and the risk of human consumption of carrots grown in Asopos River basin in Greece. A field scale experiment was conducted with carrots cultivated in treatment plots, with and without compost amendment, in order to assess the impact of carbon in the mobility and uptake of chromium by plants. The results suggested that there is a trend for chromium mobilization and uptake in the surface and the leaves of the carrots cultivated in the treatment plot with the higher carbon addition, but not in the core of the carrots. Limited mobility of hexavalent chromium in the soil-plant-water system is presented due to the affinity of chromium to be retained in the solid phase and be uptaken by plants. Hexavalent chromium tolerant bacterial strains were isolated from the carrots. These endophytic bacteria, present in all parts of the plant, were able to reduce hexavalent chromium to trivalent form to levels below the detection limit. Finally, a site-specific risk assessment analysis suggested no adverse effects to human health due to the consumption of carrots. These findings are of particular importance since they confirm that carrots grown in soils with geogenic origin chromium does not pose any adverse risk for human consumption, but could also have the beneficial effect of the micronutrient trivalent chromium.

  16. Chromium status and glucose tolerance in Saudi men with and without coronary artery disease.

    PubMed

    Alissa, Eman M; Bahjri, Suhad M; Ahmed, Waqar H; Al-Ama, Nabeel; Ferns, Gordon A A

    2009-12-01

    Chromium deficiency is associated with impaired glucose tolerance (IGT) and dyslipidemia. Hence, the objective of the current study was to investigate chromium status among Saudi men with and without established cardiovascular disease (CVD) and its relationship to glucose tolerance, lipid profile and other established CVD risk factors. We measured serum and urine chromium concentrations, fasted lipid profile, plasma glucose, and serum lipid peroxide in 130 Saudi men with an established history of myocardial infarction and 130 age-matched controls without established CVD. Patients with established CVD had higher serum triglycerides (p < 0.05) and plasma glucose (p < 0.0001) and lower serum and urinary chromium concentrations (p < 0.0001) than controls. Serum chromium was inversely correlated with plasma glucose among cases and controls (r = -0.189, p < 0.05 and r = -0.354, p < 0.00001, respectively). Plasma glucose (OR 1.127, CI 1.0-1.269, p < 0.05), serum chromium (OR 0.99, CI 0.985-0.995, p < 0.0001), and urinary chromium (OR 0.988, CI 0.981-0.995, p < 0.001) were independently associated with the presence of established coronary disease applying this model. While chromium metabolism appears to be altered in individuals with CVD, it is unclear whether chromium supplementation would be effective in CVD prevention among patients with IGT. This would need to be tested in long-term outcome trials.

  17. Bacillus species enhance growth parameters of chickpea (Cicer arietinum L.) in chromium stressed soils.

    PubMed

    Wani, Parvaze Ahmad; Khan, Mohammad Saghir

    2010-11-01

    Pollution of the agricultural land by the toxic chromium is a global threat that has accelerated dramatically since the beginning of industrial revolution. Toxic chromium affects both the microbial diversity as well as reduces the growth of the plants. Understanding the effect of the chromium reducing and plant growth promoting rhizobacteria on chickpea crop will be useful. Chromium reducing and plant growth promoting Bacillus species PSB10 significantly improved growth, nodulation, chlorophyll, leghaemoglobin, seed yield and grain protein of chickpea crop grown in the presence of different concentrations of chromium compared to the plants grown in the absence of bio-inoculant. The strain also reduced the uptake of chromium in roots, shoots and grains of chickpea crop compared to plants grown in the absence of bio-inoculant. This study thus suggested that the Bacillus species PSB10 due to its intrinsic abilities of growth promotion and attenuation of the toxic effects of chromium could be exploited for remediation of chromium from chromium contaminated sites.

  18. Hexavalent chromium in the ground and surface waters near Telluride, Colorado; preliminary data report

    USGS Publications Warehouse

    Grove, David B.; Miller, R.L.; Konikow, L.F.; O'Boyle, P. S.

    1979-01-01

    Data showing results of 38 groundwater and 25 surface-water samples analyzed for hexavalent chromium are presented. Most samples were taken within the Telluride, Colo., city limits during October 1978. Twenty-four of the 38 groundwater samples (63%) contained more than 50 micrograms per liter of hexavalent chromium. Excluding the mill tailings pond 6 of the 23 surface-water samples (26%) contained more than 50 micrograms per liter of hexavalent chromium. Hexavalent chromium concentrations in groundwaters ranged from 0 to 2700 micrograms per liter and in surface waters from 0 to 160 micrograms per liter. (USGS)

  19. Three-dimensional morphology control during wet chemical synthesis of porous chromium oxide spheres.

    PubMed

    Chen, Lifang; Song, Zhi; Wang, Xue; Prikhodko, Sergey V; Hu, Juncheng; Kodambaka, Suneel; Richards, Ryan

    2009-09-01

    Controlling the morphological evolution in nanostructures is essential for improving their functionality, for example, in catalysis. Here, we demonstrate, using chromium oxide as a model system, that morphologies of functional binary oxide particles can be tailored by an efficient template-free synthetic approach. We construct a morphological "phase diagram" for chromium oxide spheres that shows the evolution of size and surface roughness as a function of the precursor and urea concentrations. It is notable that these chromium oxide spheres show an exceptional ability to remove azo-dye pollutant in water treatment. Thus, the porous chromium oxide spheres with very good dye absorptions are expected to be useful in alternative absorption technologies.

  20. Studies on copper alloys containing chromium on the copper side phase diagram

    NASA Technical Reports Server (NTRS)

    Doi, T.

    1984-01-01

    Specimens were prepared from vacuum melted alloys of high purity vacuum melted copper and electrolytic chromium. The liquidus and eutectic point were determined by thermal analysis. The eutectic temperature is 1974.8 F and its composition is 1.28 wt% of chromium. The determination of solid solubility of chromium in copper was made by microscopic observation and electrical resistivity measurement. The solubility of chromium in solid copper is 0.6 wt% at 1050 F, 0.4 wt% at 1000 F, 0.25 wt% at 950 F, 0.17 wt% at 900 F, and 0.30 wt% at 840 F.

  1. Bioremediation of hexavalent chromium (VI) by a soil-borne bacterium, Enterobacter cloacae B2-DHA.

    PubMed

    Rahman, Aminur; Nahar, Noor; Nawani, Neelu N; Jass, Jana; Hossain, Khaled; Saud, Zahangir Alam; Saha, Ananda K; Ghosh, Sibdas; Olsson, Björn; Mandal, Abul

    2015-01-01

    Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg mL(-1) potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120-h exposure, and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.

  2. Speciation of Chromium in Soil and Sludge in the Surrounding Tannery Region, Ranipet, Tamil Nadu

    PubMed Central

    Mandal, Badal Kumar; Vankayala, Raviraj; Uday Kumar, L.

    2011-01-01

    The distribution and mobility of chromium in the soils and sludge surrounding a tannery waste dumping area was investigated to evaluate its vertical and lateral movement of operational speciation which was determined in six steps to fractionate the material in the soil and sludge into (i) water soluble, (ii) exchangeable, (iii) carbonate bound, (iv) reducible, (v) oxidizable, and (vi) residual phases. The present study shows that about 63.7% of total chromium is mobilisable, and 36.3% of total chromium is nonbioavailable in soil, whereas about 30.2% of total chromium is mobilisable, and 69.8% of total chromium is non-bioavailable in sludge. In contaminated sites the concentration of chromium was found to be higher in the reducible phase in soils (31.3%) and oxidisable phases in sludge (56.3%) which act as the scavenger of chromium in polluted soils. These results also indicate that iron and manganese rich soil can hold chromium that will be bioavailable to plants and biota. Thus, results of this study can indicate the status of bioavailable of chromium in this area, using sequential extraction technique. So a suitable and proper management of handling tannery sludge in the said area will be urgently needed to the surrounding environment as well as ecosystems. PMID:23724287

  3. Distribution, origin and fate of chromium in soils in Guanajuato, Mexico.

    PubMed

    Armienta, M A; Rodríguez, R; Ceniceros, N; Juárez, F; Cruz, O

    1996-01-01

    Total, hexavalent and trivalent chromium were determined in surface and 30-cm depth soil samples from a highly chromium-polluted area in Guanajuato state, central México. Four samples were also analyzed by a sequential extraction procedure. Nearly 0.9 km(2) out of the 8 km(2) area sampled was polluted with chromium, at concentrations up to 12960 mg kg(-1), mostly as Cr(III). Concentrations of Cr(VI) were lower than 0.5 mg kg(-1) in most sampled points, with the exception of one, where the concentration was found to be 65.14 mg kg(-1). Chromiumcontaining dust from a chromate factory accounted for most of the contamination. The highest concentrations of hexavalent chromium in soil, were in the bottom sediments of an abandoned water reservoir used to store polluted water from a well, before use of the water in the factory process. Tannery wastes, dust from a sanitary landfill of chromate compounds and the transport of chromium products are the sources of chromium at other sites. Chromium is fixed preferentially in the hydrous Fe and Mn oxides in the more polluted soils. Less polluted soils have a high proportion of chromium associated with the sulfide and organic fraction. Cr(III) is retained preferentially in the superficial soil layer. Variations in the physical characteristics of the soil, relative abundance of the various soil components and characteristics of the contaminant source, give rise to differences in chromium soil concentrations with depth.

  4. Chromium recovery from exhausted baths generated in plating processes and its reuse in the tanning industry.

    PubMed

    Torras, Josep; Buj, Irene; Rovira, Miquel; de Pablo, Joan

    2012-03-30

    Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution.

  5. Hexavalent chromium and its effect on health: possible protective role of garlic (Allium sativum Linn).

    PubMed

    Das, Kusal K; Dhundasi, Salim A; Das, Swastika N

    2011-06-17

    Hexavalent chromium or chromium (VI) is a powerful epithelial irritant and a confirmed human carcinogen. This heavy metal is toxic to many plants, aquatic animals, and bacteria. Chromium (VI) which consists of 10%-15% total chromium usage, is principally used for metal plating (H2Cr2O7), as dyes, paint pigments, and leather tanning, etc. Industrial production of chromium (II) and (III) compounds are also available but in small amounts as compared to chromium (VI). Chromium (VI) can act as an oxidant directly on the skin surface or it can be absorbed through the skin, especially if the skin surface is damaged. The prooxidative effects of chromium (VI) inhibit antioxidant enzymes and deplete intracellular glutathione in living systems and act as hematotoxic, immunotoxic, hepatotoxic, pulmonary toxic, and nephrotoxic agents. In this review, we particularly address the hexavalent chromium-induced generation of reactive oxygen species and increased lipid peroxidation in humans and animals, and the possible role of garlic (Allium sativum Linn) as a protective antioxidant.

  6. Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water.

    PubMed

    Mohan, Dinesh; Pittman, Charles U

    2006-09-21

    Hexavalent chromium is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. The most common method applied for chromate control is reduction of Cr(VI) to its trivalent form in acid (pH approximately 2.0) and subsequent hydroxide precipitation of Cr(III) by increasing the pH to approximately 9.0-10.0 using lime. Existing overviews of chromium removal only cover selected technologies that have traditionally been used in chromium removal. Far less attention has been paid to adsorption. Herein, we provide the first review article that provides readers an overview of the sorption capacities of commercial developed carbons and other low cost sorbents for chromium remediation. After an overview of chromium contamination is provided, more than 300 papers on chromium remediation using adsorption are discussed to provide recent information about the most widely used adsorbents applied for chromium remediation. Efforts to establish the adsorption mechanisms of Cr(III) and Cr(VI) on various adsorbents are reviewed. Chromium's impact environmental quality, sources of chromium pollution and toxicological/health effects is also briefly introduced. Interpretations of the surface interactions are offered. Particular attention is paid to comparing the sorption efficiency and capacities of commercially available activated carbons to other low cost alternatives, including an extensive table.

  7. Simultaneous determination of hexavalent and total chromium in water and plating baths by spectrophotometry.

    PubMed

    Gao, R M; Zhao, Z Q; Zhou, Q Z; Yuan, D X

    1993-05-01

    A new spectrophotometric determination method of hexavalent chromium in waste water and plating baths is described based on the oxidation of beryllon III by chromium(VI) in 0.02M sulphuric acid medium. The decrease in the absorbance of beryllon III was measured at 482 nm with an apparent molar absorptivity of 5.15 x 10(4)1.mole(-1).cm(-1). Beer's law was obeyed for chromium(VI) over the range 0-25 mug/25 ml. After the oxidation of Cr(III) to Cr(VI) by ammonium persulphate, total chromium can be determined. Therefore, chromium(III) can be calculated by subtracting chromium(VI) from total chromium. The detection limit is 0.015 and 0.020 mug/25 ml for chromium(VI) and total chromium, respectively. A sensitive spectrophotometric method for trace Cr(III) and Cr(VI) in waste water and plating baths was developed with good precision and accuracy. The reaction is also discussed.

  8. Allergy-Inducing Chromium Compounds Trigger Potent Innate Immune Stimulation Via ROS-Dependent Inflammasome Activation.

    PubMed

    Adam, Christian; Wohlfarth, Jonas; Haußmann, Maike; Sennefelder, Helga; Rodin, Annette; Maler, Mareike; Martin, Stefan F; Goebeler, Matthias; Schmidt, Marc

    2017-02-01

    Chromium allergy is a common occupational skin disease mediated by chromium (VI)-specific T cells that induce delayed-type hypersensitivity in sensitized individuals. Additionally, chromium (VI) can act as an irritant. Both responses critically require innate immune activation, but if and how chromium (VI) elicits this signal is currently unclear. Using human monocytes, primary human keratinocytes, and murine dendritic cells we show that chromium (VI) compounds fail to trigger direct proinflammatory activation but potently induce processing and secretion of IL-1β. IL-1β release required priming by phorbol-ester or toll-like receptor stimulation and was prevented by inhibition of K(+) efflux, NLRP3 depletion or caspase-1 inhibition, identifying chromium (VI) as a hapten activator of the NLRP3 inflammasome. Inflammasome activation was initiated by mitochondrial reactive oxygen species production triggered by chromium (VI), as indicated by sensitivity to treatment with the ROS scavenger N-acetyl cysteine and a coinciding failure of K(+) efflux, caspase-1, or NLRP3 inhibition to prevent mitochondrial reactive oxygen species accumulation. IL-1β release further correlated with cytotoxicity that was secondary to reactive oxygen species, K(+) efflux, and NLRP3 activation. Trivalent chromium was unable to induce mitochondrial reactive oxygen species production, inflammasome activation, and cytotoxicity, suggesting that oxidation state-specific differences in mitochondrial reactivity may determine inflammasome activation and allergic/irritant capacity of different chromium compounds.

  9. Progress in the chemistry of chromium(V) doping agents used in polarized target materials

    SciTech Connect

    Krumpolc, M. ); Hill, D. ); Struhrmann, H.B. , Hamburg . Hamburger Synchrotronstrahlungslabor)

    1990-01-01

    We wish to report progress in two areas of the chromium (V)-based doping agents: Two commonly used chromium (V) complexes, I and II, have been synthesized in perdeuterated form (i.e., all hydrogens replaced by deuterium). They are sodium bis(2-ethyl-2-deuteroxy-butyrato)oxochromate(V)monodeuterate, IV, (acronym EDBA-Cr(V)), and sodium bis(2-deuteroxy-2-methylpropionato)oxochromate(V), III, (acronym DMPA-Cr(V)). A synthetic route leading to the preparation of stable, chromium(III)-free solutions of chromium(V) in diols (1,2-ethanediol/ethylene glycol/and 1,2-propanediol/propylene glycol/) has been outlined.

  10. Determination of total chromium in tanned leather samples used in car industry.

    PubMed

    Zeiner, Michaela; Rezić, Iva; Ujević, Darko; Steffan, Ilse

    2011-03-01

    Despite the high competition of synthetic fibers leather is nowadays still widely used for many applications. In order to ensure a sufficient stability of the skin matrix against many factors, such as microbial degradation, heat and sweat, a tanning process is indispensable. Using chromium (III) for this purpose offers a multitude of advantages, thus this way of tanning is widely applied. During the use of chromium tanned leather as clothing material as well as for decoration/covering purposes, chromium is extracted from the leather and may then cause nocuous effects to human skin, e.g. allergic reactions. Thus the knowledge of the total chromium content of leather samples expected to come into prolonged touch with human skin is very important. In car industry leather is used as cover for seats, steering wheel and gearshift lever The chromium contents often chromium tanned leather samples used in car industry were determined. First all samples were dried at 65 degrees C overnight and then cut in small pieces using a ceramic knife, weighed and analyzed by inductively coupled plasma--optical emission spectrometry (ICP-OES) after acidic microwave assisted digestion. The total chromium amounts found were in the range from 19 mg/g up to 32 mg/g. The extraction yield of chromium from leather samples in sweat is approximately 2-7%. Thus especially during long journeys in summer chromium can be extracted in amounts which may cause nocuous effects for example on the palm of the hands or on the back.

  11. Reduction of chromium (VI) when solar selective black chromium is deposited in the presence of organic additive

    SciTech Connect

    Popov, B.N.; White, R.E. ); Slavkov, D.; Koneska, Z. )

    1992-01-01

    Electrochemical dc methods were used to study the reduction of chromium (VI) in the presence of organic additives. In this paper it is shown that F{sup +}, thiourea, and citric acid are essential to enable deposition of black chrome from concentrated chromic acid solutions. A new formulation of the plating bath is defined. The optimum operating conditions under which spectrally selective surface of black chrome is deposited have been determined.

  12. Mechanisms of hexavalent chromium resistance and removal by microorganisms.

    PubMed

    Joutey, Nezha Tahri; Sayel, Hanane; Bahafid, Wifak; El Ghachtouli, Naïma

    2015-01-01

    Chromium has been and is extensively used worldwide in multiple industrial processes and is routinely discharged to the environment from such processes. Therefore, this heavy metal is a potential threat to the environment and to public health, primarily because it is non-biodegradable and environmentally persistent. Chromium exists in several oxidation states, the most stable of which are trivalent Cr(Ill) and hexavalent Cr(VI) species. Each species possesses its own individual chemical characteristics and produces its own biological effects. For example, Cr (Ill) is an essential oligoelement for humans, whereas Cr(VI) is carcinogenic and mutagenic. Several chemical methods are used to remove Cr(VI) from contaminated sites. Each of these methods has advantages and disadvantages. Currently, bioremediation is often the preferred method to deal with Cr contaminated sites, because it is eco-friendly, cost-effective and is a "natural" technology. Many yeast, bacterial and fungal species have been assessed for their suitability to reduce or remove Cr(VI) contamination. The mechanisms by which these microorganisms resist and reduce Cr(VI) are variable and are species dependent. There are several Cr-resistance mechanisms that are displayed by microorganisms. These include active efflux of Cr compounds, metabolic reduction of Cr(VI) to Cr (ill), and either intercellular or extracellular prec1p1tation. Microbial Cr (VI) removal typically involves three stages: binding of chromium to the cell surface, translocation of chromium into the cell, and reduction of Cr(VI) to Cr (ill). Cr(VI) reduction by microorganisms may proceed on the cell surface, outside the cell, or intracellularly, either directly via chromate reductase enzymes, or indirectly via metabolite reduction of Cr(VI). The uptake of chromium ions is a biphasic process. The primary step is known as biosorption, a metabolic energyindependent process. Thereafter, bioaccumulation occurs, but is much slower, and is

  13. A Double-blind, Randomized Pilot Trial of Chromium Picolinate for Binge Eating Disorder: Results of the Binge Eating and Chromium (BEACh) Study

    PubMed Central

    Brownley, Kimberly A.; Holle, Ann Von; Hamer, Robert M.; Via, Maria La; Bulik, Cynthia M.

    2015-01-01

    Objective Chromium treatment has been shown to improve mood, appetite, and glucose regulation in various psychiatric and medical patient populations. The authors propose that chromium may be useful in the treatment of binge eating disorder (BED). Method Twenty-four overweight adults with BED were enrolled in a 6-month double-blind placebo-controlled trial and randomly assigned to receive either 1000mcg chromium/day (“high dose”; n=8) or 600mcg chromium/day (“moderate dose”; n=9) as chromium picolinate or placebo (n=7). Mixed linear regression models were used to estimate mean change in binge frequency and related psychopathology, weight, symptoms of depression, and fasting glucose. Results Fasting glucose was significantly reduced in both chromium groups compared to the placebo group; similarly, numerically, but not significantly, greater reductions in binge frequency, weight, and symptoms of depression were observed in those treated with chromium versus placebo, although statistical power was limited in this pilot trial. For fasting glucose, the findings suggest a dose response with larger effects in the high dose compared to moderate dose group. Conclusion These initial findings support further larger trials to determine chromium’s efficacy in maintaining normal glucose regulation, reducing binge eating and related psychopathology, promoting modest weight loss, and reducing symptoms of depression in individuals with BED. Studies designed to link the clinical effects of chromium with changes in underlying insulin, serotonin, and dopamine pathways may be especially informative. If efficacious, chromium supplementation may provide a useful, low-cost alternative to or augmentation strategy for selective serotonin reuptake inhibitors, which have partial efficacy in BED. ClinicalTrials.gov NCT00904306. PMID:23751236

  14. Surface Reactions Limiting Chromium(VI) Generation from Naturally Derived Chromium(III) Minerals

    NASA Astrophysics Data System (ADS)

    Hausladen, D.; Fendorf, S. E.

    2015-12-01

    Chromium(III)-bearing minerals, commonly found in serpentinite and ultramaphic rocks, are ubiquitous in California soils and along convergent plate boundaries worldwide. Elevated concentrations of carcinogenic Cr(VI) have been measured in groundwater throughout the state, even in aquifers untouched by anthropogenic contamination. In most natural systems, manganese oxides are the only known, kinetically viable, oxidant of Cr(III). Numerous laboratory studies have demonstrated a finite capacity of Mn-oxides to generate Cr(VI) before surface alterations inhibit further Cr-oxidation. The extent to which these processes dictate the inhibition, and subsequent regeneration, of Mn-oxidation capacity within structured soils and sediments is not well understood. Here we use artificial soil aggregates made of Fe(III),Cr(III)-hydroxide-coated quartz sand and surrounded by aerated solute flow (pH 8, 30mM HEPES, 10mM HCO3-) to investigate C(VI) generation within ultramafic rock derived sediment and processes inhibiting manganese reactivity. We found that while Cr(VI)-production scaled with Cr-mineral solubility; Cr(VI) effluent concentrations from aggregates of both lower and higher solubility Cr(III)-minerals peaked very soon after reaction with birnessite (within 2 days and 4 days, respectively). Once Cr(VI) production plateaued (t=22 days) aggregate influent was acidified (pH 5, 30mM C2H3O2-). Despite increasing Cr(III) solubility at lower pH, aqueous Cr(VI) production further decreased. A secondary pulse of Cr(VI) generation was seen only after the surrounding solute returned to initial conditions (pH 8). As with the initial pulse, Cr(VI) concentration scaled with mineral solubility. Collectively, our results demonstrate the extent that natural fluctuations in groundwater composition, both as a result of irrigation or precipitation events, have the potential to both regenerate and inhibit Mn-oxide surfaces. These synthetic soil aggregates provide insight into how fluctuating

  15. Thermodynamics, Kinetics, and Activation energy Studies of the sorption of chromium(III) and chromium(VI) to a Mn3O4 nanomaterial

    PubMed Central

    Cantu, Yvette; Remes, Abril; Reyna, Alejandra; Martinez, Denise; Villarreal, Jahaziel; Ramos, Hilda; Trevino, Samantha; Tamez, C.; Martinez, A.; Eubanks, T.; Parsons, J. G.

    2014-01-01

    In this study, a manganese oxide, Mn3O4 was used to remove chromium(III) and chromium(VI) from aqueous solutions. The Mn3O4 nanomaterial was synthesized through a precipitation method, and was characterized using XRD, which confirmed the material had a crystal structure similar to hausmannite. In addition, using Scherrer’s equation it was determined that the nanomaterial had an average grain size of 19.5 ± 1.10 nm. A study of the effects of pH on the binding of chromium(III) and chromium(VI) showed that the optimum binding pH was 4 and 3 respectively. Batch isotherm studies were performed to determine the binding capacity of chromium(III), which was determined to be 18.7 mg/g, 41.7 mg/g, and 54.4 mg/g respectively for 4°C, 21°C, and 45°C. Chromium(VI) on the other hand had lower binding capacities of 2.5 mg/g, 4.3 mg/g, and 5.8 mg/g for 4°C, 21°C, 45°C, respectively. Thermodynamic studies performed indicated the sorption process was for the most part controlled by physisorption. The ΔG for the sorption of chromium(III) and Chromium(VI) ranged from −0.9 to −13 kJ/mol, indicating a spontaneous reaction was occurring. The enthalpy indicated a endothermic reaction was occurring during the binding and show ΔH values of 70.6 and 19.1 kJ.mol for chromium(III) and Chromium(VI), respectively. In addition, ΔS for the reaction had positive values of 267 and 73 J/mol for chromium(III) and chromium(VI) which indicate a spontaneous reaction. In addition, the sorption process was found to follow pseudo second order kinetic and the activation energy studies indicated the binding process occurred through chemisorption. PMID:25097453

  16. Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium.

    PubMed Central

    Gao, M; Levy, L S; Faux, S P; Aw, T C; Braithwaite, R A; Brown, S S

    1994-01-01

    OBJECTIVES--Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation. METHODS--Volunteer groups of 10 workers exposed to chromium and 10 non-exposed workers provided urine and blood samples towards the end of the working week. Chromium concentrations were measured in whole blood, plasma, lymphocytes, and urine. Lymphocytes were used to examine two forms of DNA damage in the two groups; these were the level of DNA strand breakage and, the production of 8-hydroxydeoxyguanosine. RESULTS--Chromium concentration in whole blood, plasma, and urine of workers exposed to chromium was significantly raised (P < 0.01) compared with non-exposed controls, but in isolated lymphocytes, there was only a modest but significant (P < 0.05) increase in chromium in the group exposed to chromium. There was no difference in the levels of DNA strand breaks or 8-hydroxydeoxyguanosine between the groups. Air monitoring for chromium was not undertaken but current levels for the group exposed to chromium were reported to be around 0.01 mg/m3, which is 20% of the current United Kingdom occupational exposure limit. CONCLUSIONS--We were unable to detect any damage in lymphocytic DNA due to exposure to chromium. This may have been due to the low chromium exposure (< 20% of the United Kingdom occupational exposure limit), the ability of plasma to detoxify chromium (VI) to chromium (III) before it reached the lymphocytes, or perhaps the insensitivity of the molecular techniques used. It is now important to test these and other such techniques on groups exposed to levels closer to the

  17. Serum Chromium Levels in Type 2 Diabetic Patients and Its Association with Glycaemic Control

    PubMed Central

    Manikandan, Senthil; Nair, Lal Devayanivasudevan; Karuthodiyil, Rajendran; Vijayarajan, Nikhilan; Gnanasekar, Rajiv; Kapil, Vivian V.; Mohamed, Azeem S.

    2015-01-01

    Introduction Chromium is an essential micronutrient which is required for the normal functioning of insulin and regulation of blood sugar levels. It acts as a vital antioxidant for maintaining insulin homeostasis. In diabetes mellitus, the free radical production is increased and levels of antioxidants like chromium, vanadium, selenium and manganese are reduced. There have been previous studies to suggest that low serum levels of chromium are associated with poorer glycaemic control. Aim To study the level of serum chromium in newly diagnosed patients with type 2 diabetes mellitus and its association with glycaemic control. Materials and Methods Serum chromium concentration was determined by using inductively coupled Plasma – Optical Emission Spectophotometry in 42 newly diagnosed type 2 diabetes mellitus patients without any pre-existing complications. They were divided into 2 groups – well controlled (HbA1c ≤7.0%) and uncontrolled groups (HbA1c >7.0%). Results Mean serum chromium concentration measured in uncontrolled type 2 diabetic patients was significantly lower (0.065 ± 0.03 mcg/L vs 0.103 ± 0.04 mcg/L, p< 0.05). There was a statistically significant inverse linear correlation of the HbA1c values and the serum chromium concentration (r= -0.6514, p < 0.0001). There was also a decrease in chromium levels across both the groups with advancing age and the decrease being significant beyond 40 years of age (p<0.05). Conclusion The results of our study describes the relationship between serum chromium levels and control of type 2 diabetes mellitus. Significant reduction in chromium levels are probable indicators of metabolic response to oxidative stress in patients with type 2 diabetes mellitus. Further large scale studies relating serum chromium and type 2 diabetes mellitus may help to understand more about the exact relationship. PMID:26676175

  18. Studies on the biosorption of hexavalent chromium from aqueous solutions by using boiled mucilaginous seeds of Ocimum americanum.

    PubMed

    Lakshmanraj, Levankumar; Gurusamy, Ayyanar; Gobinath, M B; Chandramohan, R

    2009-09-30

    Investigations were carried out to study the chromium removal efficiency of boiled mucilaginous seeds of Ocimum americanum. Batch experiments were conducted to study the biosorption kinetics of chromium removal for the concentrations 10mg/L, 20mg/L and 40 mg/L of chromium(VI) solutions. The biosorbent dosage was 8 g dry seeds/L. The toxic hexavalent chromium was reduced to less toxic chromium(III) in the presence of seeds and the reduced chromium was adsorbed on the mucilage of seeds. Both the chromium(VI) and chromium(III) were present in the aqueous phase. The optimum chromium reduction and adsorption was observed at the pH value 1.5. The biosorption data fitted well with Langmuir isotherm. The biosorption capacity calculated from the Langmuir isotherm was q=32 mg chromium(III)/g of dry seeds. The continuous column study was also carried out at the flow rate of 27 mL/h for the initial concentration 25mg/L of chromium(VI) feed solution using a packed bed column filled with boiled mucilaginous seeds. The maximum reduction of chromium(VI) to chromium(III) in the packed bed was 80%. The percentage removal of reduced chromium from the aqueous solution was 56.25%. This value was maintained constant until 0.52 L of chromium(VI) solution was pumped through the packed bed column. Thus the naturally immobilized polysaccharides on the seeds mimic the microbial polysaccharides in terms of their ability to adsorb heavy metals with an added advantage of making the immobilization step unnecessary which is a major cost factor of the metal removal process when microbial exopolysaccharides used. The uniform size and spherical shape of swollen seeds give an additional advantage to use them in a packed bed column for continuous removal of chromium(VI) from aqueous solutions.

  19. Toxic effects and specific chromium acquired resistance in selected strains of Dyctiosphaerium chlorelloides.

    PubMed

    D'ors, A; Pereira, M; Bartolomé, M C; López-Rodas, V; Costas, E; Sánchez-Fortún, S

    2010-09-01

    Due to its various uses, chromium contamination has become widespread in a diverse array of environments. The present study was carried out to investigate the toxic effect of chromium exposures on sensitive and resistant strains of the green algae Dyctiosphaerium chlorelloides, and to determine the nature and mechanism of chromium-resistant cells that arise. The toxic effect on the photosynthetic performance of chromium exposures in both cell populations, and the sensitive differences due to chromium oxidation state, were estimated, and the results indicate that although the photosynthetic performance in both strains were inhibited, there are not significant differences among IC(50(72)) values obtained in toxicity assays with both chromium oxidation states in wild-type cells, and however these differences are very significant when the assays were performed with Cr(VI) resistant cells. The 72-h 50% inhibitory concentration values obtained with Cr(III) exposures were similar for both strains. Additionally, by means of the SEM/EDX and TEM microscopic techniques, the occurrence of rapid morphological evolution in the microalgal cells and the possible detoxificant mechanisms was observed after exposure of the wild strain to chromium hexavalent. Moreover, the different response in photosynthetic activity observed between sensitive and resistant cells of D. chlorelloides in the presence of Cr(VI) and Cr(III) could be used to obtain a chromium-specific eukaryotic microalgal biosensor.

  20. Teaching the Properties of Chromium's Oxidation States with a Case Study Method

    ERIC Educational Resources Information Center

    Ozdilek, Zehra

    2015-01-01

    The purpose of this study was to investigate how a mixed-method case study affects pre-service science teachers' awareness of hexavalent chromium pollution and content knowledge about the properties of chromium's different oxidation states. The study was conducted in Turkey with 55 sophomores during the fall semester of 2013-2014. The students…

  1. An X-Ray Diffraction Study of Chromium-Gold Thin Films.

    DTIC Science & Technology

    The chromium-gold thin films system was studied using direct recording X-ray diffraction. Chromium and/or gold thin films were deposited, in vacuum...onto glass substrates at ambient and elevated temperatures. Those thin films deposited at ambient temperatures were later annealed. The resultant X-ray

  2. Chromium supplementation enhances the acute phase response of steers to a lipopolysaccharide (LPS) challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study examined the effect of chromium supplementation on the response of steers to an LPS challenge. Twenty crossbred steers (235±4 kg BW) received 0 ppb (Control; C) or 200 ppb chromium propionate (CHR) for 55 days. Steers were fitted with jugular catheters and rectal temperature (RT) recording...

  3. The impact of humic acid on chromium phytoextraction by aquatic macrophyte Lemna minor.

    PubMed

    Kalčíková, Gabriela; Zupančič, Marija; Jemec, Anita; Gotvajn, Andreja Žgajnar

    2016-03-01

    Studies assessing chromium phytoextration from natural waters rarely consider potential implications of chromium speciation in the presence of ubiquitous humic substances. Therefore, the present study investigated the influence of environmentally relevant concentration of humic acid (TOC = 10 mg L(-1)) on chromium speciation (Cr = 0.15 mg L(-1)) and consequently on phytoextraction by aquatic macrophyte duckweed Lemna minor. In absence of humic acid, only hexavalent chromium was present in water samples and easily taken up by L. minor. Chromium uptake resulted in a significant reduction of growth rate by 22% and decrease of chlorophyll a and chlorophyll b contents by 48% and 43%, respectively. On the other hand, presence of humic acid significantly reduced chromium bioavailability (57% Cr uptake decrease) and consequently it did not cause any measurable effect to duckweed. Such effect was related to abiotic reduction of hexavalent chromium species to trivalent. Hence, findings of our study suggest that presence of humic acid and chromium speciation cannot be neglected during phytoextraction studies.

  4. Characterization and mobility of geogenic chromium in soils and river bed sediments of Asopos basin.

    PubMed

    Lilli, Maria A; Moraetis, Daniel; Nikolaidis, Nikolaos P; Karatzas, George P; Kalogerakis, Nicolas

    2015-01-08

    A field and laboratory study was conducted to assess the origin and mobility of CrVI in Asopos basin in Greece. Sampling was designed in such way as to capture the spatial variability of chromium occurring in sediments and soils in different lithological units in the area. Physicochemical and geochemical characterization of surface agricultural soils obtained from river terraces and river bed sediments was conducted in order to determine the natural background of chromium. Lithologies with strong calcareous, siliceous and ultramafic components were identified using principal component analysis. Laboratory mobility studies quantified the rates of chromium sorption and release from soils and their capacity to adsorb chromium. Heavy metal analysis and local geology study support the hypothesis that the main source of chromium is of geogenic origin. Chromium distribution in Asopos river bed was influenced from the eroded products derived from extensive areas with ultramafic rocks the last 5Ma. The mobility studies showed that leaching process was very fast and sorption capacity was significant and capable to retain chromium in case of waste release in the river. Finally the mobility of chromium release is limited due to existing attenuation capacity controlled by ferric oxides coatings on the soil and sediments.

  5. Chromium supplementation enhances the metabolic response of steers to lipopolysaccharide (LPS) challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of chromium (Cr; KemTRACE®brandChromiumProprionate 0.04%, Kemin Industries) supplementation on the metabolic response to LPS challenge was examined. Steers (n=20; 235±4 kg body weight (BW)) received a premix that added 0 (Con) or 0.2 mg/kg Cr to the total diet (DM (dry matter) basis) for ...

  6. Insulin Resistance and Body Weight: Recent Human Studies Documenting the Benefits of Supplemental Chromium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The essentiality of chromium for humans was confirmed more than three decades ago with the studies showing that patients on total parenteral nutritrion (TPN) developed severe diabetic-like symptoms that could be reversed by the addition of chromium to their parenteral nutrition solutions. Since the...

  7. Kinetics of chromium ion absorption by cross-linked polyacrylate films

    NASA Technical Reports Server (NTRS)

    May, C. E.

    1984-01-01

    Three cross-linked ion exchange membranes were studied as to their ability to absorb chromium ion from aqueous chromium III nitrate solutions. Attention was given to the mechanism of absorption, composition of the absorbed product, and the chemical bonding. The membranes were: calcium polyacrylate, polyacrylic acid, and a copolymer of acrylic acid and vinyl alcohol. For the calcium polyacrylate and the copolymer, parabolic kinetics were observed, indicating the formation of a chromium polyacrylate phase as a coating on the membrane. The rate of absorption is controlled by the diffusion of the chromium ion through this coating. The product formed in the copolymer involves the formation of a coordination complex of a chromium ion with 6 carboxylic acid groups from the same molecule. The absorption of the chromium ion by the polyacrylic acid membranes appears to be more complicated, involving cross-linking. This is due to the coordination of the chromium ion with carboxylic acid groups from more than one polymer molecule. The absorption rate of the chromium ion by the calcium salt membrane was found to be more rapid than that by the free polyacrylic acid membrane.

  8. Chromium supplementation alters the performance, metabolism, and immune response of feedlot cattle during the receiving period

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crossbreed steers (n = 180; 507 +/- 13 lb) were fed during a 56-d receiving period to determine if supplementing chromium (Cr; KemTRACEbrandChromiumPropionate 0.04%, Kemin Industries) would improve feedlot performance and health of newly received cattle. A completely randomized block design (36 pens...

  9. IN SITU TREATMENT OF SOIL AND GROUNDWATER CONTAMINATED WITH CHROMIUM - TECHNICAL RESOURCE GUIDE

    EPA Science Inventory

    New information and treatment approaches have been developed for chromium-contaminated soil and groundwater treatment. The prupose of this report is to bring together the most current information pertaining to the science of chromium contamination and the insitu treatment and co...

  10. 76 FR 20349 - Draft Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    ... Integrated Risk Information System (IRIS) AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of... Chromium: In Support of Summary Information on the Integrated Risk Information System (IRIS)'' is available..., ``Toxicological Review of Hexavalent Chromium: In Support of Summary Information on the Integrated...

  11. Isolation and characterization of chromium-resistant bacteria from tannery effluents

    SciTech Connect

    Basu, M.; Bhattacharya, S.; Paul, A.K.

    1997-04-01

    Chromium (Cr), a transition metal, is one of the major sources of environmental pollution. It is discharged into the environment through the disposal of wastes from industries like leather tanning, metallurgical and metal finishing, textiles and ceramics, pigment and wood preservatives, photographic sensitizer manufacturing, etc. In the environment chromium occurs mainly in trivalent and hexavalent forms. The hexavalent chromium (Cr{sup 6+}) compounds are comparatively much more toxic than those of trivalent chromium (Cr{sup 3+}). The reason for such toxicity appears to be due to its rapid permeability through biological membranes and subsequent interaction with intracellular proteins and nucleic acids. The tanning industry, which commonly utilizes {open_quotes}chrome liquor{close_quotes} in the tanning process, discharges the effluents into the environment containing chrome salts in excess of the maximum permissible limits. Sludge deposition from such effluents, therefore, provides a natural environment for enrichment of chromium-resistant bacteria. Chromium-resistant microorganisms from such chromium-contaminated sediments have been isolated by several investigators. The present study was an attempt to evaluate the status of chromium-resistant bacteria in the tannery effluent sediments of Calcutta-based tanning industries. 14 refs., 2 figs., 6 tabs.

  12. [Mortality of chromium plating workers in Japan--a 16-year follow-up study].

    PubMed

    Itoh, T; Takahashi, K; Okubo, T

    1996-03-01

    Health hazards due to exposure to chromium in the chromium plating industry has been documented in only a few epidemiological studies. A prospective cohort study was conducted to examine the health hazards of chromium plating with a follow-up period of over sixteen years. Subjects were 1193 male metal platers in the small-scale chromium plating plants in Tokyo. They were divided into a chromium plater subgroup (n = 623) and non-chromium plater subgroup (n = 567) and were followed up from October 1976 through December 1992. The 95% confidence interval (95%CI) of the standardized mortality ratio (SMR) was used to evaluate statistical significance. In the chromium plating subgroup, the risk of chronic hepatitis or liver cirrhosis was significantly elevated (SMR 2.34; 95%CI 1.17-4.19) and a trend toward statistical significance was seen for the risk of lung cancer (SMR 1.18; 95%CI 0.99-3.04). No significantly elevated risk was seen in the non-chromium plating subgroup. We concluded that, as the number of disease-specific deaths was small, further follow-up is necessary.

  13. 77 FR 58219 - National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-19

    ...This action finalizes the residual risk and technology review conducted for the following source categories regulated under two national emission standards for hazardous air pollutants (NESHAP): hard and decorative chromium electroplating and chromium anodizing tanks, and steel pickling--HCl process facilities and hydrochloric acid regeneration plants. On October 21, 2010, EPA proposed......

  14. Toxicity assessment and geochemical model of chromium leaching from AOD slag.

    PubMed

    Liu, Bao; Li, Junguo; Zeng, Yanan; Wang, Ziming

    2016-02-01

    AOD (Argon Oxygen Decarburization) slag is a by-product of the stainless steel refining process. The leaching toxicity of chromium from AOD slag cannot be ignored in the recycling process of the AOD slag. To assess the leaching toxicity of the AOD slag, batch leaching tests have been performed. PHREEQC simulations combined with FactSage were carried out based on the detailed mineralogical analysis and petrophysical data. Moreover, Pourbaix diagram of the Cr-H2O system was protracted by HSC 5.0 software to explore the chromium speciation in leachates. It was found that AOD slag leachate is an alkaline and reductive solution. The Pourbaix diagram of the Cr-H2O system indicated that trivalent chromium, such as Cr(OH)4(-), is the major chromium species in the experimental Eh-pH region considered. However, toxic hexavalent chromium was released with maximum concentrations of 30 µg L(-1) and 18 µg L(-1) at L/S 10 and 100, respectively, during the earlier leaching stage. It concluded that the AOD slag possessed a certain leaching toxicity. After 10 d of leaching, trivalent chromium was the dominant species in the leachates, which corresponded to the results of PHREEQC simulation. Leaching toxicity of AOD slag is based on the chromium speciation and its transformation. Great attention should be focused on such factors as aging, crystal form of chromium-enriched minerals, and electrochemical characteristics of the leachates.

  15. IN-SITU TREATMENT OF CHROMIUM SOURCE AREA USING REDOX MANIPULATION

    EPA Science Inventory

    Sodium dithionite was used to treat a chromium source zone in soils beneath an old chrome plating shop. The sodium dithionite was injected as a buffered solution into the soils to transform the chromium from the oxidized (+6) state to the reduced (+3) state. Once reduced the chro...

  16. Ecophysiological responses of young mangrove species Rhizophora apiculata (Blume) to different chromium contaminated environments.

    PubMed

    Nguyen, Kim Linh; Nguyen, Hoang Anh; Richter, Otto; Pham, Minh Thinh; Nguyen, Van Phuoc

    2017-01-01

    Many mangrove forests have suffered from the contaminated environments near industrial areas. This study addresses the question how these environments influence the renewal of mangrove forests. To this end ecophysiological responses of the young mangrove species Rhizophora apiculata (Blume) grown under combinations of the factors heavy metals (here chromium), nutrition and soil/water environment were analyzed. We tested the hypothesis that soil/water conditions and nutrient status of the soil strongly influence the toxic effect of chromium. Seedlings of R. apiculata were grown in three different soil/water environments (natural saline soil with brackish water, salt-leached soil with fresh water and salt-leached-sterilized soil with fresh water) treated with different levels of chromium and NPK fertilizer. The system was inundated twice a day as similar to natural tidal condition in the mangrove wetland in the south of Vietnam. The experiments were carried out for 6months. Growth data of root, leaf and stem, root cell number and stomata number were recorded and analyzed. Results showed that growth of R. apiculata is slower in natural saline soil/water condition. The effect of chromium and of nutrients respectively depends on the soil/water condition. Under high concentrations of chromium, NPK fertilizer amplifies the toxic effect of chromium. Stomata density increases under chromium stress and is largest under the combination of chromium and salty soil/water condition. From the data a nonlinear multivariate regression model was derived capturing the toxicity threshold of R. apiculata under different treatment combinations.

  17. Chromium Isotopes Record Fluctuations in Precambrian Biospheric Oxygenation

    NASA Astrophysics Data System (ADS)

    Frei, R.; Gaucher, C.; Poulton, S. W.; Canfield, D. E.

    2009-12-01

    There is a direct relationship between life, oxygen, and the surface chemistry of the Earth. Geochemical data suggest that oxygenation of the Earth's atmosphere occurred in two broad steps, near the beginning and the end of the Proterozoic Eon (2500 to 542 million years ago), but the details of this history are unclear. The geochemical behaviour of chromium (Cr) is highly sensitive to the redox state of the surface environment as oxidative weathering processes produce the oxidised hexavalent [Cr(VI)] form. Oxidation of reduced trivaltent [Cr(III)] chromium on land is accompanied by an isotopic fractionation, leading to enrichment of the mobile hexavalent form in the heavier isotope. The fractionated Cr isotope signature is then tranfered by riverine transport to the sea. Here, we use Cr stable isotopes from banded iron formations (BIFs) to track the presence of Cr(VI) in Precambrian oceans, providing a time-resolved picture of the oxygenation history of Earth’s atmosphere-hydrosphere system. Fractionated Cr isotopes indicate the accumulation of Cr(VI) in ocean surface waters ~2.8 to 2.6 billion years (Gyr) ago and a likely transient elevation in atmospheric and surface ocean oxygen prior to the first great rise of oxygen 2.45-2.2 Gyr ago (the Great Oxidation Event; GOE). In contrast, Cr isotopes in ~1.88 Gyr old BIFs are not fractionated, indicating a major decline in atmospheric oxygen and demonstrating that the GOE did not lead to a unidirectional stepwise increase in atmospheric oxygen. In the late Neoproterozoic, ~800 to 542 million years (Myr) ago, we observe strong positive fractionations in Cr isotopes (δ53Cr up to +4.9 ‰) providing independent support for increased surface oxygenation at this time. This may have stimulated rapid evolution of macroscopic multicellular life. Our chromium isotope data thus provide new insights into the oxygenation history of the Earth, and highlight its use as a powerful redox tracer in aquatic systems.

  18. Chromium speciation in coal and biomass co-combustion products.

    PubMed

    Stam, Arthur F; Meij, Ruud; Te Winkel, Henk; Eijk, Ronald J van; Huggins, Frank E; Brem, Gerrit

    2011-03-15

    Chromium speciation is vital for the toxicity of products resulting from co-combustion of coal and biomass. Therefore, understanding of formation processes has been studied using a combination of X-ray absorption fine structure (XAFS) spectroscopy and thermodynamic equilibrium calculations. The influence of cofiring on Cr speciation is very dependent on the type of fuel. Cr(VI) contents in the investigated fly ash samples from coal and cofiring average around 7% of the total chromium. An exception is cofiring 7-28% wood for which ashes exhibited Cr(VI) concentrations of 12-16% of the total chromium. Measurements are in line with thermodynamic predictions: RE factors of Cr around 1 are in line with volatile Cr only above 1400 °C; lower Cr(VI) concentrations with lower oxygen content and Cr(III) dissolved in aluminosilicate glass. Stability of Cr(VI) below 700 °C does not correlate with Cr(VI) concentrations found in the combustion products. It is indicated that Cr(VI) formation is a high-temperature process dependent on Cr evaporation (mode of occurrence in fuel, promoted by organic association), oxidation (local oxygen content), and formation of solid chromates (promoted by presence of free lime (CaO) in the ash). CaCrO(4)(s) is a probable chemical form but, given different leachable fractions (varying from 25 to 100%), different forms of Cr(VI) must be present. Clay-bound Cr is likely to dissolve in the aluminosilicate glass phase during melting of the clay.

  19. Computational Search for Novel Hard Chromium-Based Materials.

    PubMed

    Kvashnin, Alexander G; Oganov, Artem R; Samtsevich, Artem I; Allahyari, Zahed

    2017-02-16

    Nitrides, carbides, and borides of transition metals are an attractive class of hard materials. Our recent preliminary explorations of the binary chemical compounds indicated that chromium-based materials are among the hardest transition metal compounds. Motivated by this, here we explore in detail the binary Cr-B, Cr-C, and Cr-N systems using global optimization techniques. Calculated enthalpy of formation and hardness of predicted materials were used for Pareto optimization to define the hardest materials with the lowest energy. Our calculations recover all numerous known stable compounds (except Cr23C6 with its large unit cell) and discover a novel stable phase Pmn21-Cr2C. We resolve the structure of Cr2N and find it to be of anti-CaCl2 type (space group Pnnm). Many of these phases possess remarkable hardness, but only CrB4 is superhard (Vickers hardness 48 GPa). Among chromium compounds, borides generally possess the highest hardnesses and greatest stability. Under pressure, we predict stabilization of a layered TMDC-like phase of Cr2N, a WC-type phase of CrN, and a new compound CrN4. Nitrogen-rich chromium nitride CrN4 is a high-energy-density material featuring polymeric nitrogen chains. In the presence of metal atoms (e.g., Cr), polymerization of nitrogen takes place at much lower pressures; CrN4 becomes stable at ∼15 GPa (cf. 110 GPa for synthesis of pure polymeric nitrogen).

  20. Chromium(III) complexes of naturally occurring ligands

    NASA Astrophysics Data System (ADS)

    El-Shahawi, M. S.

    1995-02-01

    Chromium(III) complexes prepared from CrCl 3Py 3 and anhydrous CrCl 3 with L(-)-threonine, nicotinic acid, glycine, D(-)-penicillamine, L(-)-cysteine and L(-)-cystine have been characterized. The magnetic moments (3.4-4.05 B.M.) are close to the spin only value for a d3 chromium(III) ion in octahedral or pseudo octahedral symmetry. In the electronic spectra two sharp peaks are observed at (15.9-19.8) × 10 3 and (22.0-26.7) × 10 3 cm -1 and are assigned to d-d transitions in the pseudo octahedral configuration. The parameters ( Dq, B, β35) and the interelectronic repulsion parameter with the ionic charge, Z∗, are calculated and place the ligand in the middle of the spectrochemical series. In the circular dichroism spectra three Cotton effects are observed in the forbidden band of the optically active chelates and are assigned to the 2E( 2Eg), 2A 2( 2T 1g) and2E( 2T 1g) while that in the spin allowed band are a result of the splitting of the 4A 2g( 4T 2g) to 4A 1( 4T 2g) and4E( 4T 2g) transitions. The structure of threonine, cystine and cysteine chelates are likely to be fac since strong and well defined Cotton effects are observed. The Cotton effects of penicillamine chelates are weak suggesting formation of the mer structure. Prolonged heating or bubbling air through the solution of CrCl 3Py 3 containing L(-)-threonine, glycine or nicotinic acid for several hours enhances chromium(VI) formation.

  1. Redox Equilibria of Chromium in Calcium Silicate Base Melts

    NASA Astrophysics Data System (ADS)

    Mirzayousef-Jadid, A.-M.; Schwerdtfeger, Klaus

    2009-08-01

    The oxidation state of chromium has been determined at 1600 °C in CaO-SiO2-CrO x melts with CaO/SiO2 ratios (mass pct) of 0.66, 0.93, and 1.10, and 0.15 to 3.00 pct Cr2O3 (initial). A few experiments were also carried out with CaO-SiO2-Al2O3-CrO x melts at 1430 °C. The slag samples were equilibrated with gas phases of controlled oxygen pressure. Two techniques were applied to determine the oxidation state: thermogravimetry and quenching of the samples with subsequent wet chemical analysis. In the low-oxygen pressure range, the chromium is mainly divalent. In the high-oxygen pressure range, it is trivalent and hexavalent. It was found that the Cr3+/Cr2+ and Cr6+/Cr3+ ratios depend on oxygen pressure at a constant CaO/SiO2 ratio and a constant content of total chromium, according to the ideal law of mass action. According to the respective chemical reactions, these ratios change proportional to p_{{{text{O}}2 }}{}^{1/4} or p_{{{text{O}}_{ 2} }}{}^{3/4}, respectively. They also increase with increasing basicity. The data are used to compute the fractions of the different ions in the melt. There is a certain range of oxygen pressure in which all three valence states, Cr2+, Cr3+, and Cr6+, coexist. The color of the solidified slag samples is described and is explained with the help of transmission spectra.

  2. Chromium removal from electroplating wastewater by coir pith.

    PubMed

    Suksabye, Parinda; Thiravetyan, Paitip; Nakbanpote, Woranan; Chayabutra, Supanee

    2007-03-22

    Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2% (w/v) dosage, particle size <75microm, at initial Cr(VI) 1647mgl(-1), system pH 2, and an equilibrium time of 18h. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15, 30, 45 and 60 degrees C was 138.04, 197.23, 262.89 and 317.65mgCr(VI)g(-1) coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FT-IR) spectrometry analysis indicated that the carbonyl (CO) groups and methoxy (O-CH(3)) groups from the lignin structure in coir pith may be involved in the mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with CO groups and O-CH(3) groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III).

  3. On Some Features of Chromium Carbide Diffusion Layer Formation

    NASA Astrophysics Data System (ADS)

    Glowacki, Z.; Kaluba, W.

    1982-05-01

    The formation of chromium carbide diffusion layers on iron-carbon alloys was studied in this investigation. The investigation was carried out on graphite, plain carbon steels, gray cast iron, and white cast iron. The carbide layers were obtained by the powder pack method. To distinguish the effect of iron from the chromizing medium on the layer morphology, high purity iron and chromium powders were used as the components of the powder mixture. The samples were chromized in the temperature range of 870 to 1373 K for five to 1500 minutes. Phase composition of the layers was examined by X-ray diffraction method. To assess chromium and iron distribution in the layers, an electron micro-probe was employed. Microstructure of the layers was examined with the aid of light and electron microscopes. Both replica and thin foil methods were used in this work. The original method of thin foil preparation was used to show the M7C3 layer substructure and to define its crystallographic orientation. It was found that formation of the carbide layer began at temperatures below A1 transformation, when the samples were heated to a normal chromizing temperature. It was proved that M3C appearance in the layer depends on both chromizing temperature and amount of carbon in the alloy. The Fe : Cr ratio in the chromized medium was found to affect the microstructure and thickness of the layers strongly. The needle-shaped grains of the M7C3 layer showed particular crystallographic orientation, i.e., [0001] M7C3 crystallographic direction was perpendicular to the diffusion front. The new data on microstructure of the carbide layers were obtained by thin foil method. The growth direction of the carbide layer was defined, which allowed the suggestion of the diffusion model for the carbide layer formation.

  4. Free energy and phase diagram of chromium alloys

    SciTech Connect

    Fishman, R.S. ); Liu, S.H. )

    1993-08-01

    The phase diagram of chromium alloys is remarkably rich. At the Neel temperature of 310 K, pure chromium undergoes a weakly first-order phase transition into an incommensurate spin-density wave (SDW) state. When doped with more than 0.2% manganese, this transition becomes second order and the SDW becomes commensurate. Over 25 years ago, Koehler [ital et] [ital al]. and Komura, Hamaguchi, and Kunitomi observed a first-order commensurate-to-incommensurate (CI) transition in CrMn alloys. The temperature of this CI transition decreased to zero as the manganese concentration increases from about 0.2% to about 1.5%. Using mean-field theory, we have constructed the free energy and phase diagram of chromium alloys in the presence of electron scattering. In the absence of scattering, the phase diagram allows a first-order phase transition from the incommensurate to the commensurate states with decreasing temperature. But if the damping is sufficiently large, the phase-separation curve flips from the right side of the tricritical point to the left. So within a small window of manganese concentrations, the commensurate state undergoes a first-order transition into the incommensurate state with decreasing temperature, in agreement with the experiments of Koehler [ital et] [ital al]. At zero temperature, we find a first-order phase transition from the incommensurate to the commensurate state with manganese doping, in agreement with the work of Komura, Hamaguchi, and Kunitomi. In the absence of damping, the zero-temperature energy gap [Delta](0) in the commensurate regime is independent of manganese concentration. But in the presence of damping [Delta](0) becomes an increasing function of the manganese concentration.

  5. Free energy and phase diagram of chromium alloys

    NASA Astrophysics Data System (ADS)

    Fishman, R. S.; Liu, S. H.

    1993-08-01

    The phase diagram of chromium alloys is remarkably rich. At the Néel temperature of 310 K, pure chromium undergoes a weakly first-order phase transition into an incommensurate spin-density wave (SDW) state. When doped with more than 0.2% manganese, this transition becomes second order and the SDW becomes commensurate. Over 25 years ago, Koehler et al. and Komura, Hamaguchi, and Kunitomi observed a first-order commensurate-to-incommensurate (CI) transition in CrMn alloys. The temperature of this CI transition decreased to zero as the manganese concentration increases from about 0.2% to about 1.5%. Using mean-field theory, we have constructed the free energy and phase diagram of chromium alloys in the presence of electron scattering. In the absence of scattering, the phase diagram allows a first-order phase transition from the incommensurate to the commensurate states with decreasing temperature. But if the damping is sufficiently large, the phase-separation curve flips from the right side of the tricritical point to the left. So within a small window of manganese concentrations, the commensurate state undergoes a first-order transition into the incommensurate state with decreasing temperature, in agreement with the experiments of Koehler et al. At zero temperature, we find a first-order phase transition from the incommensurate to the commensurate state with manganese doping, in agreement with the work of Komura, Hamaguchi, and Kunitomi. In the absence of damping, the zero-temperature energy gap Δ(0) in the commensurate regime is independent of manganese concentration. But in the presence of damping Δ(0) becomes an increasing function of the manganese concentration.

  6. Chromium removal by zeolite-rich materials obtained from an exhausted FCC catalyst: Influence of chromium incorporation on the sorbent structure.

    PubMed

    Gonzalez, Maximiliano R; Pereyra, Andrea M; Torres Sánchez, Rosa M; Basaldella, Elena I

    2013-10-15

    A spent FCC catalyst was converted into a zeolitic mixture, and the product obtained was afterward used as trapping material for Cr(III) species frequently found in aqueous solutions. Eventual changes in the sorbent structure produced by Cr incorporation were studied by different characterization techniques such as point of zero charge determinations (PZC), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and infrared absorption (FTIR). The XRD and FTIR analyses indicated that chromium incorporation produces an amorphization of the material, and PZC measurements show no surface adsorption of charged chromium species. SEM and EDX analyses clearly show that after chromium sorption, the initial microspheroidal catalyst morphology was maintained, and the presence of chromium species was mainly detected in the outer microsphere surface, where the zeolite crystals were hydrothermally grown.

  7. Type 2 Diabetic Rats on Diet Supplemented With Chromium Malate Show Improved Glycometabolism, Glycometabolism-Related Enzyme Levels and Lipid Metabolism

    PubMed Central

    Feng, Weiwei; Zhao, Ting; Mao, Guanghua; Wang, Wei; Feng, Yun; Li, Fang; Zheng, Daheng; Wu, Huiyu; Jin, Dun; Yang, Liuqing; Wu, Xiangyang

    2015-01-01

    Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the effect of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism in type 2 diabetic rats. Our results showed that fasting blood glucose, serum insulin level, insulin resistance index and C-peptide level in the high dose group had a significant downward trend when compared with the model group, chromium picolinate group and chromium trichloride group. The hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, Glut4, phosphor-AMPKβ1 and Akt levels in the high dose group were significantly higher than those of the model, chromium picolinate and chromium trichloride groups. Chromium malate in a high dose group can significantly increase high density lipoprotein cholesterol level while decreasing the total cholesterol, low density lipoprotein cholesterol and triglyceride levels when compared with chromium picolinate and chromium trichloride. The serum chromium content in chromium malate and chromium picolinate group is significantly higher than that of the chromium trichloride group. The results indicated that the curative effects of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism changes are better than those of chromium picolinate and chromium trichloride. Chromium malate contributes to glucose uptake and transport in order to improved glycometabolism and glycometabolism-related enzymes. PMID:25942313

  8. Type 2 diabetic rats on diet supplemented with chromium malate show improved glycometabolism, glycometabolism-related enzyme levels and lipid metabolism.

    PubMed

    Feng, Weiwei; Zhao, Ting; Mao, Guanghua; Wang, Wei; Feng, Yun; Li, Fang; Zheng, Daheng; Wu, Huiyu; Jin, Dun; Yang, Liuqing; Wu, Xiangyang

    2015-01-01

    Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the effect of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism in type 2 diabetic rats. Our results showed that fasting blood glucose, serum insulin level, insulin resistance index and C-peptide level in the high dose group had a significant downward trend when compared with the model group, chromium picolinate group and chromium trichloride group. The hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, Glut4, phosphor-AMPKβ1 and Akt levels in the high dose group were significantly higher than those of the model, chromium picolinate and chromium trichloride groups. Chromium malate in a high dose group can significantly increase high density lipoprotein cholesterol level while decreasing the total cholesterol, low density lipoprotein cholesterol and triglyceride levels when compared with chromium picolinate and chromium trichloride. The serum chromium content in chromium malate and chromium picolinate group is significantly higher than that of the chromium trichloride group. The results indicated that the curative effects of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism changes are better than those of chromium picolinate and chromium trichloride. Chromium malate contributes to glucose uptake and transport in order to improved glycometabolism and glycometabolism-related enzymes.

  9. 76 FR 58536 - Tin- and Chromium-Coated Steel Sheet From Japan; Notice of Commission Determination To Conduct a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-21

    ... COMMISSION Tin- and Chromium-Coated Steel Sheet From Japan; Notice of Commission Determination To Conduct a Full Five-Year Review Concerning the Antidumping Duty Order on Tin- and Chromium-Coated Steel Sheet... on tin- and chromium-coated steel sheet from Japan would be likely to lead to continuation...

  10. 40 CFR 721.10239 - Trivalent chromium complexes of a substituted beta-naphthol amine azo dye (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Trivalent chromium complexes of a... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10239 Trivalent chromium complexes of... subject to reporting. (1) The chemical substance identified generically as trivalent chromium complexes...

  11. 40 CFR 721.10239 - Trivalent chromium complexes of a substituted beta-naphthol amine azo dye (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Trivalent chromium complexes of a... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10239 Trivalent chromium complexes of... subject to reporting. (1) The chemical substance identified generically as trivalent chromium complexes...

  12. 21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Chromium (Cr III) complex of N-ethyl-N... Substances for Use Only as Components of Paper and Paperboard § 176.160 Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N-ethyl -...

  13. 40 CFR 721.10239 - Trivalent chromium complexes of a substituted beta-naphthol amine azo dye (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Trivalent chromium complexes of a... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10239 Trivalent chromium complexes of... subject to reporting. (1) The chemical substance identified generically as trivalent chromium complexes...

  14. Evaluating Foraminifera as an Archive for Seawater Chromium Isotopic Composition

    NASA Astrophysics Data System (ADS)

    Wang, X.; Planavsky, N.; Hull, P. M.; Tripati, A.; Reinhard, C.; Zou, H.; Elder, L. E.; Henehan, M. J.

    2015-12-01

    In recent years there has been growing interest in using chromium isotopes (δ53Cr) as a proxy to investigate the redox evolution of Earth's ocean-atmosphere system throughout geological history. Potential archives for seawater δ53Cr that have been identified to date include iron formations and organic-rich siliciclastic sediments. However, these types of sediments are not common and they are discontinuous over geologic time. As a result, alternative types of archives are needed. Here we evaluate the utility of foraminifera tests as a recorder of seawater δ53Cr. Core-tops used were from different ocean basins. Mono-specific samples of Globigerinoides sacculifer, Orbulina universa, Pulleniatina obliquiloculata, Globoratalia crassula-crassaformis, Globoratalia truncatulinoides, and Globigerinella siphonifera were isolated to investigate inter-species isotope fractionation. Chromium concentrations were measured by isotope dilution method to be 0.1-0.3 μg/g. The δ53Cr values of these species range from 0.2‰ to 2.4‰, with an analytical uncertainty of 0.3‰ (95% confidence). Despite the high analytical uncertainty due to the extremely low levels of Cr present, there is still large detectable variation in foraminiferal δ53Cr values, which overlap presently available seawater values (Bonnand et al., 2013; Scheiderich et al., 2015). Possible explanations for such variations in foraminiferal δ53Cr values include heterogeneity of seawater δ53Cr in the modern oceans, and/or photobiochemical redox cycling of Cr in the surface oceans. Therefore, care should be taken when using foraminifera to reconstruct past seawater δ53Cr values. ReferencesBonnand, P., James, R., Parkinson, I., Connelly, D., Fairchild, I., 2013. The chromium isotopic composition of seawater and marine carbonates. Earth and Planetary Science Letters, 382: 10-20. Scheiderich, K., Amini, M., Holmden, C., Francois, R., 2015. Global variability of chromium isotopes in seawater demonstrated by Pacific

  15. Heat treatment of cobalt-chromium alloy wire.

    PubMed

    Fillmore, G M; Tomlinson, J L

    1976-04-01

    This study shows that the ability of cobalt-chromium wire to resist permanent deformation is definitely affected by the temperature of heat treatment. For each temperature of heat treatment up to 1200 degrees F there is progressively greater resistance to permanent deformation; at temperatures of heat treatment above 1200 degrees F, however, there is a rapid decline in resistance to permanent deformation due to partial annealing. The maximum resistance to permanent deformation occurs from heat treatment in the temperature range of 1100 degrees to 1200 degrees F. A clinician desiring maximum resistance to permanent deformation from a .016 inches x .022 inches cobalt-chromium archwire should heat-treat the wire at 1100 degrees to 1200 degrees F for 5 minutes in a dental furnace. If the wire was in a highly work-hardened condition as were the wire specimens of this study, he could expect an increase in resistance to permanent deformation of approximately 174 percent. Heat treatment at lower temperatures could be used in situations requiring less than maximum resistance to permanent deformation. Heat treatment at 900 degrees F would give approximately a 95 percent increase in resistance to permanent deformation. Of course, heat treatment would not be indicated when the desired level of resistance to permanent deformation was not greater than the amount exhibited in the untreated wires of this study. When an electrical resistance heat-treatment unit and 950 degrees F temper-indicating paste were used, the clinician would expect increased resistance to permanent deformation similar to that seen in the wires heat-treated with a dental furnace at 800 degrees and 900 degrees F, i.e., about half of that obtained by the 1200 degrees F treatment. This study has determined the effects that various temperatures of heat treatment have on the resistance to permanent deformation of cobalt-chromium wire specimens which were formed into a specific pattern of loops. The following

  16. Structural, morphological and optical properties of chromium oxide nanoparticles

    SciTech Connect

    Babukutty, Blessy; Parakkal, Fasalurahman; Nair, Swapna S.; Bhalero, G. M.; Aravind, P. B.

    2015-06-24

    Chromium oxide nanoparticles are synthesized by reduction route from chloride precursors with surfactant, trioctylphosphine oxide (TOPO). Structural and morphological characterization are analyzed using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Transmission Electron micrographs show that the average grain size lies in the range 5nm to 10nm. Optical characterization has been done by UV-VIS spectrophotometer. Distinct optical absorptions of Cr{sup 3+} ions show hinting towards the presence of Cr{sub 2}O{sub 3}. Presence of oxygen is also confirmed from Electron Energy Loss Spectroscopy (EELS) studies.

  17. Fractography of hydrogen-embrittled iron-chromium-nickel alloys

    SciTech Connect

    Caskey, G.R. Jr.

    1981-01-01

    Tensile specimens of iron-chromium-nickel base alloys were broken in either a hydrogen enviroment or in air following thermal charging with hydrogen. Fracture surfaces were examined by scanning electron microscopy. Fracture morphology of hydrogen-embrittled specimens was characterized by: changed dimple size, twin-boundary parting, transgranular cleavage, and intergranular separation. The nature and extent of the fracture mode changes induced by hydrogen varied systematically with alloy composition and test temperature. Initial microstructure developed during deformation processing and heat treating had a secondary influence on fracture mode.

  18. Chromium(II)-catalyzed enantioselective arylation of ketones

    PubMed Central

    Wang, Gang; Sun, Shutao; Mao, Ying; Xie, Zhiyu

    2016-01-01

    The chromium-catalyzed enantioselective addition of carbo halides to carbonyl compounds is an important transformation in organic synthesis. However, the corresponding catalytic enantioselective arylation of ketones has not been reported to date. Herein, we report the first Cr-catalyzed enantioselective addition of aryl halides to both arylaliphatic and aliphatic ketones with high enantioselectivity in an intramolecular version, providing facile access to enantiopure tetrahydronaphthalen-1-ols and 2,3-dihydro-1H-inden-1-ols containing a tertiary alcohol. PMID:28144349

  19. Industry participation workshop: Chromium electroplating of superconductor strand. Proceedings

    SciTech Connect

    1994-12-13

    The primary objective of the workshop was to inform US plating vendors about the opportunity to participate in the effort on Cr plating of large quantities of superconducting wires required for the ITER and the TPX projects and DOE`s interest in developing several reliable and high quality suppliers of Chromium plating services for the superconducting strand industry. The objective was also to inform plating vendors about the Cr plating technology developed in LLNL and invite interested plating vendors to get the technology. Finally the workshop was intended to inform the plating vendors about the plan to get verification of capability of two to four vendors for Cr plating of superconducting strands.

  20. Reflections on hexavalent chromium: health hazards of an industrial heavyweight.

    PubMed

    Pellerin, C; Booker, S M

    2000-09-01

    Chromium has been used commercially in the United States for more than 100 years in metal alloys and other compounds, as a pigment, and in the tanning and metal plating industries, and many studies have looked at its effects in terms of occupational health. But, although scientists know that Cr(VI) is a human carcinogen and that it can cause other deleterious health effects including kidney and liver damage, certain questions remain about the metal's effects, such as which routes of exposures are dangerous for humans.

  1. Physiological changes induced by chromium stress in plants: an overview.

    PubMed

    Hayat, Shamsul; Khalique, Gulshan; Irfan, Mohammad; Wani, Arif Shafi; Tripathi, Bhumi Nath; Ahmad, Aqil

    2012-07-01

    This article presents an overview of the mechanism of chromium (Cr) stress in plants. Toxic effects of Cr on plant growth and development depend primarily on its valence state. Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Cr-induced oxidative stress involves induction of lipid peroxidation in plants that cause severe damage to cell membranes which includes degradation of photosynthetic pigments causing deterioration in growth. The potential of plants with the adequacy to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained engrossment in recent years.

  2. Proton exchange membrane fuel cells with chromium nitridenanocrystals as electrocatalysts

    SciTech Connect

    Zhong, Hexiang; Chen, Xiaobo; Zhang, Huamin; Wang, Meiri; Mao,Samuel S.

    2007-07-01

    Polymer electrolyte membrane fuel cells (PEMFCs) are energy conversion devices that produce electricity from a supply of fuel, such as hydrogen. One of the major challenges in achieving efficient energy conversion is the development of cost-effective materials that can act as electrocatalysts for PEMFCs. In this letter, we demonstrate that, instead of conventional noble metals, such as platinum, chromium nitride nanocrystals of fcc structure exhibit attractive catalytic activity for PEMFCs. Device testing indicates good stability of nitride nanocrystals in low temperature fuel cell operational environment.

  3. Chromium Renderserver: Scalable and Open Source Remote RenderingInfrastructure

    SciTech Connect

    Paul, Brian; Ahern, Sean; Bethel, E. Wes; Brugger, Eric; Cook,Rich; Daniel, Jamison; Lewis, Ken; Owen, Jens; Southard, Dale

    2007-12-01

    Chromium Renderserver (CRRS) is software infrastructure thatprovides the ability for one or more users to run and view image outputfrom unmodified, interactive OpenGL and X11 applications on a remote,parallel computational platform equipped with graphics hardwareaccelerators via industry-standard Layer 7 network protocolsand clientviewers. The new contributions of this work include a solution to theproblem of synchronizing X11 and OpenGL command streams, remote deliveryof parallel hardware-accelerated rendering, and a performance analysis ofseveral different optimizations that are generally applicable to avariety of rendering architectures. CRRSis fully operational, Open Sourcesoftware.

  4. MODELING THE RATE-CONTROLLED SORPTION OF HEXAVALENT CHROMIUM.

    USGS Publications Warehouse

    Grove, D.B.; Stollenwerk, K.G.

    1985-01-01

    Sorption of chromium VI on the iron-oxide- and hydroxide-coated surface of alluvial material was numerically simulated with rate-controlled reactions. Reaction kinetics and diffusional processes, in the form of film, pore, and particle diffusion, were simulated and compared with experimental results. The use of empirically calculated rate coefficients for diffusion through the reacting surface was found to simulate experimental data; pore or particle diffusion is believed to be a possible rate-controlling mechanism. The use of rate equations to predict conservative transport and rate- and local-equilibrium-controlled reactions was shown to be feasible.

  5. Risk of lung cancer among former chromium smelter workers.

    PubMed

    Rosenman, K D; Stanbury, M

    1996-05-01

    Hexavalent chromium is a known carcinogen. Previous epidemiologic studies in the 1950s of United States workers from seven facilities producing chromium compounds from chromite ore have reported a markedly increased risk for dying from lung cancer. As part of a high risk notification project of workers from four of these facilities, a mortality study was performed. The cohort was assembled in 1990-1991 from the Social Security records of four former chromate producing facilities in northern New Jersey. The study subjects were known to have worked at these facilities some time between 1937 and 1971. Proportionate mortality and proportionate cancer mortality ratios (PCMR) were calculated. The overall risk for lung cancer was a PCMR of 1.51 (confidence limits [CL] 1.29-1.74) for white men and 1.34 (CL 1.00-1.75) for black men. These risks increased with increasing duration of employment and latency since time of first employment. The PCMR for greater than 20 years duration of work and more than 20 years since first exposure was 1.94 (CL 1.15-3.06) for white men and 3.08 (CL 1.13-6.71) for black men. The risk for lung cancer for white men remains elevated more than 20 years after exposure has ceased (PCMR, 1.29; CL 1.03-1.60). The PCMR for nasal cavity/sinus cancer was also found to be a significantly increased, 5.18 (CL 2.37-11.30). A cluster of bladder cancer was seen among black workers from one facility, (PCMR, 3.30; CL 1.42-6.51). Despite the cessation of exposure, former chromium workers remain at significantly increased risk of lung cancer. Although there have been case reports of nasal cavity/ sinus cancer in association with chromium exposure, this is the first epidemiologic study to report a significant increase in these cancers. Limitations in this study include lack of exposure data and lack of information on smoking habits. The lack of increase in other smoking-related diseases besides lung cancer indicates that the increase in lung cancer cannot be

  6. Luminescent properties of alumina ceramics doped with chromium oxide

    NASA Astrophysics Data System (ADS)

    Kortov, V.; Kiryakov, A.; Pustovarov, V.

    2016-08-01

    Ceramics doped with chromium oxide were synthesized from alumina nanopowder at high heating and cooling rates. XRD analysis of the obtained samples shows that they consist mainly of Al2O3 α-phase. Photoluminescence (PL) spectra in the visible spectral region and thermoluminescence (TL) curves were measured. An effect of the dopant concentration on the intensity and shape of the PL bands as well as on the TL yield was found. Annealing of the quenching defects which emerged during the synthesis changed the PL spectra. The centers responsible for PL and TL in the synthesized ceramics were identified.

  7. Reflections on hexavalent chromium: health hazards of an industrial heavyweight.

    PubMed Central

    Pellerin, C; Booker, S M

    2000-01-01

    Chromium has been used commercially in the United States for more than 100 years in metal alloys and other compounds, as a pigment, and in the tanning and metal plating industries, and many studies have looked at its effects in terms of occupational health. But, although scientists know that Cr(VI) is a human carcinogen and that it can cause other deleterious health effects including kidney and liver damage, certain questions remain about the metal's effects, such as which routes of exposures are dangerous for humans. PMID:11017901

  8. Information profiles on potential occupational hazards: Inorganic chromium compounds. Draft report (Second)

    SciTech Connect

    Not Available

    1982-02-01

    Information profiles are presented for the following inorganic chromium compounds: chromic(VI) acid, chromic(III) hydroxide, chromic(III) oxide, chromic(III) sulfate, chromic(III) sulfate (basic), chromium dioxide, potassium dichromate(VI), lead chromate, sodium-chromate(VI), sodium-dichromate(VI), and zinc-yellow-chromate(VI). Biological effects of hexavalent chromium in humans included skin ulceration, dermatitis, nasal membrane irritation and ulceration, nasal septal perforation, rhinitis, nosebleed, nephritis, liver damage, epigastric pain, pulmonary congestion and edema, and erosion and discoloration of teeth. Chromium(VI) compounds caused mutations in a variety of systems. Exposure to trivalent chromium in the work place has caused contact dermatitis and chrome ulcers. Epidemiological studies indicated respiratory carcinogenicity among workers occupationally exposed during chromate production.

  9. Stability of chromium (III) sulfate in atmospheres containing oxygen and sulfur

    NASA Technical Reports Server (NTRS)

    Jacob, K. T.; Rao, B. D.; Nelson, H. G.

    1978-01-01

    The stability of chromium sulfate in the temperature range from 880 K to 1040 K was determined by employing a dynamic gas-solid equilibration technique. The solid chromium sulfate was equilibrated in a gas stream of controlled SO3 potential. Thermogravimetric and differential thermal analyses were used to follow the decomposition of chromium sulfate. X-ray diffraction analysis indicated that the decomposition product was crystalline Cr2O3 and that the mutual solubility between Cr2(SO4)3 and Cr2O3 was negligible. Over the temperature range investigated, the decomposition pressure were significantly high so that chromium sulfate is not expected to form on commercial alloys containing chromium when exposed to gaseous environments containing oxygen and sulfur (such as those encountered in coal gasification).

  10. Reaction layer formation at the graphite/copper-chromium alloy interface

    NASA Technical Reports Server (NTRS)

    Devincent, Sandra M.; Michal, Gary M.

    1993-01-01

    Sessile drop tests were used to obtain information about copper chromium alloys that suitably wet graphite. Characterization of graphite/copper-chromium alloy interfaces subjected to elevated temperatures were conducted using scanning electron micrography, energy dispersive spectroscopy, Auger electron spectroscopy, and X-ray diffraction analyses. These analyses indicate that during sessile drop tests conducted at 1130 C for one hour, copper alloys containing greater than 0.98 percent chromium form continuous reaction layers of approximately 10 micron thickness. The reaction layers adhere to the graphite surface. The copper wets the reaction layer to form a contact angle of 60 degrees or less. X-ray diffraction results indicate that the reaction layer is chromium carbide. The kinetics of reaction layer formation were modelled in terms of bulk diffusion mechanisms. Reaction layer thickness is controlled initially by the diffusion of Cr out of Cu alloy and later by the diffusion of C through chromium carbide.

  11. Reaction layer formation at the graphite/copper-chromium alloy interface

    NASA Technical Reports Server (NTRS)

    Devincent, Sandra M.; Michal, Gary M.

    1992-01-01

    Sessile drop tests were used to obtain information about copper chromium alloys that suitably wet graphite. Characterization of graphite/copper-chromium alloy interfaces subjected to elevated temperatures were conducted using scanning electron micrography, energy dispersive spectroscopy, auger electron spectroscopy, and x ray diffraction analyses. These analyses indicate that during sessile drop tests conducted at 1130 C for one hour, copper alloys containing greater than 0.98 percent chromium form continuous reaction layers of approximately 10 micron thickness. The reaction layers adhere to the graphite surface. The copper wets the reaction layer to form a contact angle of 60 degrees or less. X ray diffraction results indicate that the reaction layer is chromium carbide. The kinetics of reaction layer formation were modelled in terms of bulk diffusion mechanisms. Reaction layer thickness is controlled initially by the diffusion of Cr out of Cu alloy and later by the diffusion of C through chromium carbide.

  12. Comments on article "Toxicity and carcinogenicity of chromium compounds in humans" by Costa and Klein.

    PubMed

    Post, Gloria B; Stern, Alan H

    2006-10-01

    The recent article by Costa and Klein (2006) contains several inaccuracies about the federal drinking water standard for chromium. The federal drinking water standard for chromium is 100 ppb, not 50 ppb as stated by Costa and Klein, and it is based on non-carcinogenic effects, not a one in one million cancer risk level. The question of whether or not hexavalent chromium is carcinogenic via the oral route is the focus of much current interest and has major implications for regulation of chromium in drinking water and soil. The chronic drinking water study of hexavalent chromium currently being conducted by the National Toxicology Program will provide further information that will be useful in addressing this question.

  13. Development of Alkaline Oxidative Dissolution Methods for Chromium (III) Compounds Present in Hanford Site Tank Sludges

    SciTech Connect

    NN Krot; VP Shilov; AM Fedoseev; NA Budantseva; MV Nikonov; AB Yusov; AYu Garnov; IA Charushnikova; VP Perminov; LN Astafurova; TS Lapitskaya; VI Makarenkov

    1999-07-02

    The high-level radioactive waste sludge in the underground storage tanks at the Hanford Site contains various chromium(III)solid phases. Dissolution and removal of chromium from tank waste sludges is desirable prior to high-level waste vitrification because increased volume is required to incorporate the residual chromium. Unfortunately, dissolution of chromium from the sludge to form Cr(OH){sub 4}{sup {minus}} through treatment with heated NaOH solution (also used to dissolve aluminum phases and metathesize phosphates to sodium salts) generally has been unsuccessful in tests with both simulated and genuine Hanford waste sludges. Oxidative dissolution of the Cr(III) compounds to form soluble chromate has been proposed as an alternative chromium solid phase dissolution method and results of limited prior testing have been reported.

  14. Chromium Contamination in Leon Valley Mexico: Insights from Chromium Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Villalobos-Aragon, A.; Ellis, A. S.; Armienta, M. A.; Morton, O.; Johnson, T. M.; Glessner, J. J.

    2008-12-01

    Chromium (Cr) is a contaminant commonly found in surface and groundwater. In nature Cr commonly occurs in two valences: Cr(VI) is highly mobile, toxic and carcinogenic, while Cr(III) is less mobile. Cr was first detected in groundwater in the Leon Valley region (located in central Mexico) in 1975 (Rodriguez and Armienta, 1995). Previous work proposed an anthropogenic origin for a high concentration plume near the industrial Buenavista (BV), while the larger sub ppb plume located near San Juan de Otates (SJO) is assumed to be caused by weathering of the SJO pyroxenite. Cr stable isotopes have been shown to be useful in monitoring reduction and can also be used to infer redox and transport conditions in natural settings and the goals of our research are: 1) use stable isotope values (δ53Cr) to monitor Cr behavior in the Leon Valley, 2) identify sources (industrial vs. weathering of ultramafic rocks). Since 1975, the highly contaminated BV area is showing a decrease in groundwater Cr(VI) concentrations. Our sampling in 2007 show Cr(VI) concentrations decreasing from 0.005mg/l to 121mg/l to 0.002mg/l to 95.1mg/l. However, the Cr waste piles still exit and Cr(VI) concentrations from leachate collection ponds range from 1.2g/l to 6.8g/l. Isotopic values obtained from leaching experiments performed on the waste pile samples show enriched δ53Cr values (0.76‰ to 3.25‰) either indicating varying reduction or that the waste is fractionated during the ore processing. δ53Cr values for groundwater range from 0.33‰ to 0.46‰, indicating minimal reduction and lack of available reducing agents. The lack of variation of isotopic values seen in the groundwater plume is also consistent with the results of previous studies showing insignificant fractionation due to sorption within the plume (Villalobos-Aragon et al., 2008). The unfractionated Cr(VI) in groundwater vs. those of the waste piles, considered the contamination source, suggests that either 1) the Cr in the waste

  15. Chromium and zinc contamination of parenteral nutrient solution components commonly used in infants and children.

    PubMed

    Hak, E B; Storm, M C; Helms, R A

    1998-01-15

    Chromium and zinc contamination of components of parenteral nutrient (PN) solutions used in infants and children was studied. Solutions of amino acids, L-cysteine hydrochloride, dextrose, electrolytes, minerals, vitamins, multiple trace elements, and individual trace elements were obtained. A variety of manufacturers, lots, and expiration dates were represented when possible. The solutions were analyzed for chromium and zinc by flame atomic absorption spectrophotometry. In all amino acid products, chromium concentration was below the limit of detection and zinc concentration ranged from 0.06 to 4.97 mg/L. In the L-cysteine hydrochloride products, chromium was measurable in only two lots (0.11 and 0.23 mg/L); zinc was measurable in all lots (32-86 mg/L). Sodium and potassium salts of chloride and acetate had chromium concentrations of 0.02-0.23 mg/L and zinc concentrations of 0.35-0.56 mg/L. Phosphate salts contained chromium 0.39-0.44 mg/L and zinc 0.91-2.33 mg/L. In calcium gluconate, zinc concentration was 0.28-2.38 mg/L. In four lots of multiple trace elements, chromium was 92-104% and zinc was 100-113.5% of the labeled amount. A PN solution for a < 10-kg infant compounded from the components assayed would provide up to an additional 0.7 microgram of chromium per kilogram and 200 micrograms of zinc per kilogram. Zinc and chromium contaminants were detected in many of the products that are common components of PN solutions for infants and children; the contamination may be sufficient to result in the administration of zinc and chromium in amounts exceeding current recommendations.

  16. [Measured and Predicted Aquatic Life Criteria and Risk Assessment of Chromium (VI) in Liaohe River].

    PubMed

    Wang, Xiao-nan; Yan, Zhen-guang; Liu, Zheng-tao; Zhang, Cong; Wang, Wei-li

    2015-07-01

    In this study, toxicity data of aquatic species in Liaohe River for heavy metal chromium (VI) was collected and selected. The aquatic life criteria for chromium (VI) in Liaohe River was derived based on these toxicity data. Moreover, water samples of 25 sites in Liaohe River were collected, and the concentrations of chromium (VI) in these samples were analyzed. Finally, ecological risk assessment of chromium (VI) in Liaohe River was performed. Moreover, interspecies correlation estimation method (ICE) established by US EPA was used to predict the acute toxicity of species in Liaohe River, and aquatic life criteria based on predicted toxicity data was derived. The results showed that: the measured CMC (criteria maximum concentration), measured CCC (criteria continuous concentration) and the predicted CMC were 17. 73, 12. 15 and 13. 97 µg . L -1, respectively. Therefore, the ICE method could be used to predict the aquatic life criteria, because the predicted criteria value was very similar to the measured criteria value. Analysis of chromium (V) showed that the chromium (VI) concentrations of the 25 sites in Liaohe River were all below Class I or Class II water quality standards (GB 3838-2002), and the water quality was in good condition. However, for the potential risk of chromium (VI) exposure to the aquatic life of Liaohe River, the result of ecological risk assessment showed that chromium (V) concentrations in 7 sites exceeded the CCC in July, and chromium (VI) concentrations in 6 sites exceeded the CCC in December. Therefore, unacceptable effect on aquatic species caused by chromium (VI) exposure might have occurred in some sites of Liaohe River.

  17. Errors and interferences in the determination of chromium in biological materials by INAA

    SciTech Connect

    Becker, D.A. )

    1993-01-01

    In the late 1950s, chromium was found to be important in animal nutrition, and shortly after that was found to be essential for human nutrition. The most important chromium function is in maintaining normal glucose tolerance primarily by regulating insulin action, although the exact molecular structure involved has not yet been determined. In addition, some interaction of chromium with thyroid metabolism and with nucleic acids in both experimental animals and humans has been postulated. However, dietary intake of chromium in the United States and in other developed countries is reported to be suboptimal by 30 to 50%, based on the minimum US daily intake of 50 [mu]g. There are analytical problems with the determination of chromium in biological materials by most analytical techniques, including neutron activation analysis (NAA). The well-known International Atomic Energy Agency (IAEA) intercomparison on milk powder produced results for chromium by 13 laboratories ranging over more than four orders of magnitude. More recently, the 1990 American Society for Testing and Materials task group intercomparison on apple leaves initially produced results having a range of 483% for the four laboratories reporting chromium. The peach leaves results were similar with a range of 450%. Note also that these latter two intercomparisons were on botanical matrices having relatively high chromium concentrations of [approximately] 0.3 and 1 mg/kg, compared to the IAEA milk with a concentration of 0.02 mg/kg. This paper reports on potential errors and interferences which can enter into chromium measurements by INAA. Some errors discussed are generic, applying to any measurement system, and some are specific to the problem of chromium in biological matrices.

  18. Bioavailability of chromium in soils and sediments at a former leather tannery site

    SciTech Connect

    Pacquin, P.R.; Di Toro, D.M.; De Rosa, L.; Maiello, J.; Kerrigan, J.

    1995-12-31

    Bioavailability is a fundamental consideration in the equilibrium partitioning method used by EPA to develop sediment quality criteria (SOC). Even so, the bioavailability of metals in soils and sediments is often overlooked in ecological risk assessments for Superfund sites. This paper summarizes field and laboratory data for chromium levels in biota, soil and sediment samples from an abandoned tannery site and presents a method for characterizing the bioavailable fraction of chromium in these media. Chromium levels in soils and sediments at the former tannery site are about 1,000 times higher than levels at control sites (30,000 ppm versus 30 ppm). The elevated chromium levels are due to previously released tannery wastes, which contain high levels of chromium as a result of the tanning process. In contrast to chromium levels in soils and sediments, levels in terrestrial biota (earthworms, vegetation, and meadow voles) and aquatic biota (minnows, crayfish and mayfly nymphs) at the site are only about 2 to 20 times higher than control area samples. Biota:Soil and Biota:Sediment Accumulation Factors (BSAFs, total chromium basis) for the site are about one to five percent of control area BSAFs. This difference indicates that chromium at the site is relatively non-bioavailable. Sequential extraction techniques were used to characterize the manner in which the chromium is bound to soil and sediment at the site. The extraction results are compared with the biota field data and it appears that the exchangeable chromium fraction is indicative of the bioavailable fraction. The implications of these results to a screening level ecological risk assessment are presented.

  19. Insulin sensitising action of chromium picolinate in various experimental models of diabetes mellitus.

    PubMed

    Shindea, Urmila A; Sharma, Geeta; Xu, Yan J; Dhalla, Naranjan S; Goyal, Ramesh K

    2004-01-01

    Although chromium is an essential element for carbohydrate and lipid metabolism, its effects in diabetic patients are still debated. We have studied the effect of 6 week treatment with chromium picolinate (8 microg/ml in drinking water) in streptozotocin (STZ)-induced type 1 and type 2 diabetic rat models. The mechanism of anti-diabetic action of chromium picolinate was studied using C2C12 myoblasts and 3T3-L1 adipocytes. Chromium picolinate significantly decreased the area under the curve over 120 min for glucose of both STZ-induced type 1 (40mg/kg, i.v. in adult rats) and type 2 (90 mg/kg, i.p. in 2 day old rat neonates) diabetic rats without any significant change in area under the curve over 120 min for insulin as compared to controls. The composite insulin sensitivity index and insulin sensitivity index (KITT) values of both type 1 and type 2 diabetic rats were increased significantly by chromium picolinate. Treatment with chromium picolinate produced a significant decrease in elevated cholesterol and triglyceride levels in both types of diabetic rats. In 3T3-L1 adipocytes, chromium picolinate (0-10 micromol) per se did not produce any effect, however, when co-incubated with insulin it significantly increased the intracellular triglyceride synthesis (EC50 = 363.7nmol/1). Similarly in C2C12 myoblasts, chromium picolinate alone did not produce any effect, however, it significantly increased insulin-induced transport of 14C-glucose. In conclusion, chromium picolinate significantly improves deranged carbohydrate and lipid metabolism of experimental chemically induced diabetes in rats. The mechanism of in vivo anti-diabetic action appears to be peripheral (skeletal muscle and adipose tissue) insulin enhancing action of chromium.

  20. A Research Investigation of Possibilities for Obtaining Hot-Hard Electrodeposited Chromium or Chromium-Base Alloys for Cannon

    DTIC Science & Technology

    1952-02-09

    by subjecting the specimen to a 2-second electrolytic etch in 10 per cent oxalic acid at 3 volts and 80 F. Figure 10 shows a cross-sectional view of...DEPOSIT BEFORE BONDING HEAT TREATMENT. BASIS METAL IS 4140 GUN-TUBE STEEL 250X Two-second electrolytic etch in 10 % 85022 oxalic acid at 3... oxalic acid at 3 volts and 80 F FIGURE 9. CROSS SECTION OF A CHROMIUM-IRON DEPOSIT AFTER BONDING HEAT TREATMENT AT 750 F FOR FOUR HOURS (Note the

  1. CH-47F Improved Cargo Helicopter (CH-47F)

    DTIC Science & Technology

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-278 CH-47F Improved Cargo Helicopter (CH-47F) As of FY 2017 President’s Budget Defense...Estimate RDT&E - Research, Development, Test, and Evaluation SAR - Selected Acquisition Report SCP - Service Cost Position TBD - To Be Determined TY

  2. Investigate of atmospheric arsenic, cadmium, chromium, lead, and mercury levels in moss species found around Zilkale, by EDXRF Spectrometry

    NASA Astrophysics Data System (ADS)

    Akçay, Nilay; Batan, Nevzat; Ćinar, Yunus

    2016-04-01

    Zilkale is a castle located in Fırtına Valley and it is one of the most important historical structures in Çamlihemşin district of Rize Province in the Black Sea Region of Turkey. The castle surrounded by very high mountains that poke up into the clouds, and it rains here all year round. Tourism businesses or industrial plants are not so much there yet. In recent years, Zilkale region has begun the attract tourist, people on treaking holidays in the Kaçkar. But many domestic and foreign tourists come to this region by own car or tour buses. The aim of this study is to investigate the atmospheric concentrations of arsenic, cadmium, chromium, lead, and mercury levels in five different moss species collected around Zilkale by using Energy Dispersive X-ray Fluorescence (EDXRF) Spectrometry. The average concentrations of heavy metals in moss samples ranged from 0.79-4.63 ppm for arsenic, 54.47-143.39 ppm for chromium, 39.97-81.03 ppm for lead. The values of cadmium and mercury were found below the detection limit. This study has shown that Hypnum cupressiforme, Abietinella abietina, Rhytidium rugosum, Plagiomnium undulate, and Thuidium tamariscinum samples collected around Zilkale were used to assess the potential contamination of atmospheric As, Cd, Cr, Pb, Hg contamination in the region and made important contributions toward the understanding of atmospheric As, Cd, Cr, Pb, Hg baseline data can be used for identification of changes in the levels of these heavy metals in the studied area.

  3. Humoral and cellular immunity in chromium picolinate-supplemented lambs.

    PubMed

    Dallago, B S L; McManus, C M; Caldeira, D F; Campeche, A; Burtet, R T; Paim, T P; Gomes, E F; Branquinho, R P; Braz, S V; Louvandini, H

    2013-08-01

    The effects of oral supplementation of chromium picolinate (CrPic) on humoral and cellular immunity in sheep were investigated. Twenty-four male lambs divided into four treatments and received different dosages of CrPic: placebo (0), 0.250, 0.375, and 0.500 mg of chromium/animal/day during 84 days. The base ration was Panicum maximum cv Massai hay and concentrate. Blood samples were collected fortnightly for total and differential leukocyte counts. On days 28 and 56, the lambs were challenged with chicken ovalbumin I.M. Serum samples were collected on days 46 and 74 and subjected to an indirect enzyme-linked immunosorbent assay to measure IgG anti-ovalbumin. The cell-mediated immune response was determined by a delay-type hypersensitivity test using phytohemagglutinin. CrPic did not significantly affect humoral immunity in lambs but there was a negative effect on cellular immunity (P < 0.05) as Cr supplementation increased. Therefore, the level of Cr supplementation for lambs must be better studied to address its effect on stressed animals or the possible toxic effects of Cr on the animal itself or its immune system.

  4. Speciation of chromium in bread and breakfast cereals.

    PubMed

    Mathebula, Mpho Wendy; Mandiwana, Khakhathi; Panichev, Nikolas

    2017-02-15

    Bread and breakfast cereals are a major constituents of the human diet, yet their Cr(VI) content is not known. Chromium(VI) was determined in these products by high resolution continuum source atomic absorption spectrometer (HR-CS AAS) after leaching Cr(VI) with 0.10molL(-1) Na2CO3. The results showed that 33-73% of total Cr (58.17±5.12μgkg(-1)-156.1±6.66μgkg(-1)) in bread exist as Cr(VI) and the highest total Cr content was found in brown bread. It was shown that Cr(III) is oxidized to Cr(VI) during toasting of bread. Chromium(VI) content in breakfast cereals ranged between 20.4±4μgkg(-1) and 470.4±68μgkg(-1). Therefore, it can be concluded that bread and breakfast cereals contains Cr(VI) which does not exceed maximum acceptable concentration (MAC) of 0.003mgkg(-1)bw(-1)day(-1) through daily consumption of half a bowl (65g) of breakfast cereal and four slices of toasted (122g) or untoasted bread (160g).

  5. Extraction and recovery of chromium from electroplating sludge.

    PubMed

    de Souza E Silva, Paula Tereza; de Mello, Nielson Torres; Menezes Duarte, Marta Maria; Montenegro, M Conceição B S M; Araújo, Alberto N; de Barros Neto, Benício; da Silva, Valdinete Lins

    2006-01-16

    This work reports a study of the extraction and recovery of chromium from the wastes (class I dangerous) generated by a galvanic manufacturer. Commercial HCl at room temperature was employed, and the conditions of the extraction process were optimized according to a sequential experimental design, which also included the acid concentration and contact time as variables. The best extraction conditions (80% v/v; 30 min; 97.6% Cr) for the chromic sludge were chosen in order to make the recovery process economically feasible. After each extraction, the residue was submitted to leaching essays, to assess environmental risks. It was found that sludge could be characterized as no longer dangerous. In the recovery study, a simple and low-cost technique was evaluated for selectivity based on an oxidation step with hydrogen peroxide. A 2(3) factorial design to assess the influence of oxidation time (min), temperature ( degrees C) and peroxide amount (mol/L) was employed. The best conditions, yielding a chromium recovery of about 92%, were a time of 60 min, a temperature of 60 degrees C and 2.1 mol/L peroxide. Additional essays revealed that the same result could be obtained with more economic conditions (40 min, 1.4 mol/L peroxide and 60 degrees C). This technique proved not only effective in comparison with existing alternatives, but also low costing.

  6. Biosorption of aqueous chromium(VI) by Tamarindus indica seeds.

    PubMed

    Agarwal, G S; Bhuptawat, Hitendra Kumar; Chaudhari, Sanjeev

    2006-05-01

    The effectiveness of low cost agro-based materials namely, Tamarindus indica seed (TS), crushed coconut shell (CS), almond shell (AS), ground nut shell (GS) and walnut shell (WS) were evaluated for Cr(VI) removal. Batch test indicated that hexavalent chromium sorption capacity (q(e)) followed the sequence q(e)(TS) > q(e)(WS) > q(e)(AS) > q(e)(GS) > q(e)(CS). Due to high sorptive capacity, tamarind seed was selected for detailed sorption studies. Sorption kinetic data followed first order reversible kinetic fit model for all the sorbents. The equilibrium conditions were achieved within 150 min under the mixing conditions employed. Sorption equilibria exhibited better fit to Freundlich isotherms (R>0.92) than Langmuir isotherm (R approximately = 0.87). Hexavalent chromium sorption by TS decreased with increase in pH, and slightly reduced with increase in ionic strength. Cr(VI) removal by TS seems to be mainly by chemisorption. Desorption of Cr(VI) from Cr(VI) laden TS was quite less by distilled water and HCl. Whereas with NaOH, maximum desorption achieved was about 15.3%. When TS was used in downflow column mode, Cr(VI) removal was quite good but head loss increased as the run progressed and was stopped after 200 h.

  7. Erosion of iron-chromium alloys by glass particles

    NASA Technical Reports Server (NTRS)

    Salik, J.; Buckley, D. H.

    1984-01-01

    The material loss upon erosion was measured for several iron-chromium alloys. Two types of erodent material were used: spherical glass beads and sharp particles of crushed glass. For erosion with glass beads the erosion resistance (defined as the reciprocal of material loss rate) was linearly dependent on hardness. This is in accordance with the erosion behavior of pure metals, but contrary to the erosion behavior of alloys of constant composition that were subjected to different heat treatments. For erosion with crushed glass, however, no correlation existed between hardness and erosion resistance. Instead, the erosion resistance depended on alloy composition rather than on hardness and increased with the chromium content of the alloy. The difference in erosion behavior for the two types of erodent particles suggested that two different material removal mechanisms were involved. This was confirmed by SEM micrographs of the eroded surfaces, which showed that for erosion with glass beads the mechanism of material removal was deformation-induced flaking of surface layers, or peening, whereas for erosion with crushed glass it was cutting or chopping.

  8. Density functional theory and chromium: Insights from the dimers

    SciTech Connect

    Würdemann, Rolf; Kristoffersen, Henrik H.; Moseler, Michael; Walter, Michael

    2015-03-28

    The binding in small Cr clusters is re-investigated, where the correct description of the dimer in three charge states is used as criterion to assign the most suitable density functional theory approximation. The difficulty in chromium arises from the subtle interplay between energy gain from hybridization and energetic cost due to exchange between s and d based molecular orbitals. Variations in published bond lengths and binding energies are shown to arise from insufficient numerical representation of electron density and Kohn-Sham wave-functions. The best functional performance is found for gradient corrected (GGA) functionals and meta-GGAs, where we find severe differences between functionals from the same family due to the importance of exchange. Only the “best fit” from Bayesian error estimation is able to predict the correct energetics for all three charge states unambiguously. With this knowledge, we predict small bond-lengths to be exclusively present in Cr{sub 2} and Cr{sub 2}{sup −}. Already for the dimer cation, solely long bond-lengths appear, similar to what is found in the trimer and in chromium bulk.

  9. Boriding of high carbon high chromium cold work tool steel

    NASA Astrophysics Data System (ADS)

    Muhammad, W.

    2014-06-01

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30% B4C, 70% borax at 950 °C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 μm. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc wer test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time.

  10. In Situ Treatment of Chromium-Contaminated Groundwater

    SciTech Connect

    Fruchter, Jonathan S. )

    2002-12-01

    In Situ Treatment of Chromate Contaminated Groundwater Jonathan S. Fruchter Pacific Northwest National Laboratory Abstract of paper published in Environmental Science and Technology, 2002 Although not as common as solvent or fuel products contamination, chromate (chromium (VI)) contamination of groundwater is relatively widespread. Chromate has a variety of industrial uses, including chrome plating, steel making, and use as a corrosion inhibitor, wood preservative, well-drilling fluid additive, biocide, and as a pigment in paints and primers. EPA has estimated that as many as 1300 sites in the United States may have groundwater contaminated with chromate. The paper discusses a number of approaches to in situ treatment of chromate contamination in groundwater aquifers. The approaches include various types of chemical treatments, biological treatments and natural attenuation. The strengths and weaknesses of each method are discussed and compared. Field examples of two types of chemical treatment, in situ redox manipulation and chemically enhanced pump and treat are presented. It is concluded that in situ methods show promise, but can be difficult to implement due to site-specific conditions and limited long-term experience with these methods. As more performance and cost data are acquired for the demonstrations that are ongoing, and continuing research increases our understanding of subsurface processes, in situ treatment methods for chromium (VI) contamination in groundwater should gain wider acceptance.

  11. Treatment of chromium plating process effluents with ion exchange resins.

    PubMed

    Tenório, J A; Espinosa, D C

    2001-01-01

    The surface treatment industry deals with various heavy metals, including the elements Cr, Zn, Ni, Cd, and Cu. Conventional treatments of effluents generate class I solid residue. The aim of this investigation was to study the viability of ion exchange as an alternative process for treatment of rinse water and to determine the efficacy of two ion exchange systems, System 1: "strong" cationic resin-"strong" anionic resin and System 2: "strong" cationic resin-"weak" anionic resin. Commercial resins and solutions taken from rinse tanks of chromium plating companies were used in this investigation. A two-column system, one for the cationic resin and another for the anionic resin, both with 150 ml capacity was mounted. The solution was percolated at a rate of 10 ml/min. The following solutions were used for regeneration of the resins: 2% H2SO4 for the cationic and 4% NaOH for the anionic. The percolated solutions revealed chromium contents of less than 0.25 mg/l, independent of the system used. The "strong" cationic resin-"weak" anionic resin gave excellent regeneration results. The "strong" cationic-"strong" anionic resin presented problems during regeneration, and did not release the retained ions after percolation of 2000 ml of 4% NaOH solution. It is concluded that for this type of treatment, the system composed of "strong" cationic resin and "weak" anionic resin is more appropriate.

  12. Venturi/vortex technology for controlling chromium electroplating emissions

    SciTech Connect

    Hay, K.J.; Northrup, J.; Heck, S.R.

    1997-12-31

    A new technology has been developed to control air emissions from hexavalent chromium electroplating tanks. The venturi/vortex scrubber uses a patented drain assembly to pull plating solution, air with toxic particulates above the solution, and unpopped bubbles of generated gases down with a gravity generated vortex effect. The recirculated plating solution acts as the scrubbing liquid and air agitation is eliminated. Separated gases are passed through a condenser/filter to remove any remaining fumes. The device is almost entirely constructed of CPVC. This device offers several advantages over conventional end-of-pipe systems including significantly lower cost, no wastewater, no extensive ventilation system, and emissions are recycled. The system can be is easily retrofitted to existing tanks, however, a loose fitting tank lid is recommended. A pilot demonstration has been performed at Benet Laboratory, Watervliet, NY (US Army) with a 1,500 gallon chromic acid electroplating tank and 1,500 Amps of applied current. Overall chromium emissions results were 0.00002 mg/Amp-hr, surpassing the stringent California State requirement of 0.006 mg/Amp-hr. Emission prevention by capturing unpopped bubbles is the method in which this system reduces the most emissions. The system met current ambient worker safety standards. Two major improvements are recommended: an increase in gas flow rate through the system and a solution to the system`s sensitivity to the plating solution level.

  13. Genetic Predisposition for Dermal Problems in Hexavalent Chromium Exposed Population

    PubMed Central

    Sharma, Priti; Bihari, Vipin; Agarwal, Sudhir K.; Goel, Sudhir K.

    2012-01-01

    We studied the effect of genetic susceptibility on hexavalent chromium induced dermal adversities. The health status of population was examined from the areas of Kanpur (India) having the elevated hexavalent chromium levels in groundwater. Blood samples were collected for DNA isolation to conduct polymorphic determination of genes, namely: NQO1 (C609T), hOGG1 (C1245G), GSTT1, and GSTM1 (deletion). Symptomatic exposed subjects (n = 38) were compared with asymptomatic exposed subjects (n = 108) along with asymptomatic controls (n = 148) from a non contaminated reference community. Exposed symptomatic group consisted of 36.8% subjects who were GSTM1 null genotyped as compared to asymptomatic where only 19.4% subjects were null. The exposed subjects with GSTM1 null genotype were more susceptible to dermal adversities in comparison with wild genotyped subjects (OR = 2.42; 95% CI = 1.071–5.451). Age, smoking, gender or duration of residence were not found to have any confounding effect towards this association. Association with other genes was not statistically significant, nonetheless, possible contribution by these genes cannot be ruled out. In conclusion, variation in the polymorphic status of GSTM1 gene may influence dermal outcomes among residents from Cr(VI) contaminated areas. Further studies are therefore, needed to examine these observations among different population groups. PMID:22919465

  14. Hexavalent chromium induces chromosome instability in human urothelial cells.

    PubMed

    Wise, Sandra S; Holmes, Amie L; Liou, Louis; Adam, Rosalyn M; Wise, John Pierce

    2016-04-01

    Numerous metals are well-known human bladder carcinogens. Despite the significant occupational and public health concern of metals and bladder cancer, the carcinogenic mechanisms remain largely unknown. Chromium, in particular, is a metal of concern as incidences of bladder cancer have been found elevated in chromate workers, and there is an increasing concern for patients with metal hip implants. However, the impact of hexavalent chromium (Cr(VI)) on bladder cells has not been studied. We compared chromate toxicity in two bladder cell lines; primary human urothelial cells and hTERT-immortalized human urothelial cells. Cr(VI) induced a concentration- and time-dependent increase in chromosome damage in both cell lines, with the hTERT-immortalized cells exhibiting more chromosome damage than the primary cells. Chronic exposure to Cr(VI) also induced a concentration-dependent increase in aneuploid metaphases in both cell lines which was not observed after a 24h exposure. Aneuploidy induction was higher in the hTERT-immortalized cells. When we correct for uptake, Cr(VI) induces a similar amount of chromosome damage and aneuploidy suggesting that the differences in Cr(VI) sensitivity between the two cells lines were due to differences in uptake. The increase in chromosome instability after chronic chromate treatment suggests this may be a mechanism for chromate-induced bladder cancer, specifically, and may be a mechanism for metal-induced bladder cancer, in general.

  15. Upgrading ferrochromium to chromium by nitriding, leaching, and dissociation

    NASA Astrophysics Data System (ADS)

    Kirby, A. W.; Fray, D. J.

    1989-04-01

    A process for the upgrading of the chromium content of ferrochromium powder has been investigated on a laboratory scale. The overall process consists of nitriding the ferrochromium to form Fe4N and CrN, which exist as two separate phases. In acidic solution, Fe4N reacts readily, whereas under certain conditions, CrN is inert; this offers a selective way of removing the iron phase. Finally, the CrN can be dissociated under moderate vacuum at elevated temperatures to yield chromium containing 2 pct iron and less than 0.05 pct nitrogen. The kinetics and equilibria of nitriding using nitrogen and ammonia have been studied as a function of temperature and gas composition. X-ray powder diffraction identified CrN, Cr2N, FeN, and Fe4N with the relative proportions varying with the nitriding conditions. As the lower nitride Cr2N, which formed on nitriding above 1073 K, was found to be susceptible to attack by acids, the iron was leached from samples nitrided below 1073 K where the products consisted of CrN and Fe4N. The optimum efficiency of iron leaching was found to depend upon the nitriding and leaching times, leaching temperatures, stirring rates, and acid concentrations. The dissociation of CrN was examined in a vacuum furnace, and dissociation was found to proceed rapidly above 1423 K.

  16. A post-remediation assessment in Jersey City of the association of hexavalent chromium in house dust and urinary chromium in children.

    PubMed

    Black, Kathleen; Gochfeld, Michael; Lioy, Paul J; Fan, Zhi-Hua Tina; Yu, Chang Ho; Jeitner, Chris; Hernandez, Marta; Einstein, Stephanie A; Stern, Alan H

    2015-01-01

    Although all chromite ore processing residue (COPR) sites near residential neighborhoods in Jersey City, New Jersey have undergone remediation, recent studies found widespread, but low levels of hexavalent chromium (Cr(+6)) in house dust both in Jersey City and in communities with no known sources of Cr(+6). This study was designed as a follow-up to determine whether there is an association between current Cr(+6) levels in house dust and urinary chromium concentrations in young children. Dust samples (N=369) were collected from 123 homes. The median Cr(+6) concentration was 3.3 μg/g (mean±SD 5.2±7.5) and the median Cr(+6) loading was 1.1 μg/m(2) (1.9±3.1). These levels were not elevated compared with previously reported levels in background communities (median concentration=3.5 μg/g; median loading=2.8 μg/m(2)). Urinary chromium concentrations were measured in spot urine samples collected from 150 children, ages 3 months to 6 years. The median uncorrected urinary chromium concentration was 0.19 μg/l (0.22±0.16). Current urinary chromium concentrations were significantly lower than those previously reported before and during remediation (t-test; P<0.001). Urinary chromium concentrations were not significantly higher in homes with high (75th or 90th percentile) Cr(+6) dust levels (concentration or loading) compared with other homes. Multiple linear regression was used to examine the relationship between Cr(+6) levels (concentration and loading) in house dust and urinary chromium concentrations (uncorrected and specific gravity corrected). Contrary to pre-remediation studies, we did not find a positive association between Cr(+6) levels in house dust and urinary chromium concentrations. The findings indicate that current Cr(+6) levels in house dust are not positively associated with children's chromium exposure as measured by urinary chromium, and the children's exposure to Cr(+6) in house dust is below the level that could be identified by urine

  17. Adverse effects and bioconcentration of chromium in two freshwater rotifer species.

    PubMed

    Hernández-Ruiz, Esmeralda; Alvarado-Flores, Jesús; Rubio-Franchini, Isidoro; Ventura-Juárez, Javier; Rico-Martínez, Roberto

    2016-09-01

    Bioaccumulation of trivalent (CrIII) and hexavalent chromium (CrVI), and its adverse effects were studied in two rotifer species: Brachionus calyciflorus (two different strains), and Lecane quadridentata. Median Lethal Concentration (LC50) at 24 h of both species showed that CrVI is highly toxic: LC50 ranges from 4.7 × 10(-5) to 4 × 10(-6) mg L(-1)), compared with CrIII: LC50 ranges from 0.64 to 1.279 mg L(-1). Using the LC50 as an exposure concentration, and using atomic absorption, the bioconcentration factor (BCF) was obtained and BCFs of rotifers exposed to CrIII are four orders of magnitude lower than BCFs of rotifers exposed to CrVI. The effect of Cr on the elemental composition of the two species of rotifers in their structures by X-ray microanalysis by energy dispersion showed that Cr is found in intoxicated rotifers, but not in control rotifers. The basal immunoreactivity to metallothioneins is greater in B. calyciflorus than L. quadridentata. The immunoreactivity to metallothioneins decreases in B. calyciflorus when is exposed to CrIII, in contrast in L. quadridentata the immunoreactivity to metallothioneins increase when is exposed to CrIII, and the immunoreactivity to CrVI in L. quadridentata decrease. A mechanism is proposed in which the harder lorica of L. quadridentata acts as a barrier and accumulator of CrVI, and allows for attenuating responses like metallothionein production in L. quadridentata. Instead, in B. calyciflorus the lack of a harder lorica allows for deeper penetration of CrVI, and no time to produce attenuating measures.

  18. A novel method for blood volume estimation using trivalent chromium in rabbit models

    PubMed Central

    Baby, Prathap Moothamadathil; Kumar, Pramod; Kumar, Rajesh; Jacob, Sanu S.; Rawat, Dinesh; Binu, V. S.; Karun, Kalesh M.

    2014-01-01

    Background: Blood volume measurement though important in management of critically ill-patients is not routinely estimated in clinical practice owing to labour intensive, intricate and time consuming nature of existing methods. Aims: The aim was to compare blood volume estimations using trivalent chromium [51Cr(III)] and standard Evans blue dye (EBD) method in New Zealand white rabbit models and establish correction-factor (CF). Materials and Methods: Blood volume estimation in 33 rabbits was carried out using EBD method and concentration determined using spectrophotometric assay followed by blood volume estimation using direct injection of 51Cr(III). Twenty out of 33 rabbits were used to find CF by dividing blood volume estimation using EBD with blood volume estimation using 51Cr(III). CF is validated in 13 rabbits by multiplying it with blood volume estimation values obtained using 51Cr(III). Results: The mean circulating blood volume of 33 rabbits using EBD was 142.02 ± 22.77 ml or 65.76 ± 9.31 ml/kg and using 51Cr(III) was estimated to be 195.66 ± 47.30 ml or 89.81 ± 17.88 ml/kg. The CF was found to be 0.77. The mean blood volume of 13 rabbits measured using EBD was 139.54 ± 27.19 ml or 66.33 ± 8.26 ml/kg and using 51Cr(III) with CF was 152.73 ± 46.25 ml or 71.87 ± 13.81 ml/kg (P = 0.11). Conclusions: The estimation of blood volume using 51Cr(III) was comparable to standard EBD method using CF. With further research in this direction, we envisage human blood volume estimation using 51Cr(III) to find its application in acute clinical settings. PMID:25190922

  19. [Simultaneous determination of trivalent chromium and hexavalent chromium in plastics by accelerated solvent extraction-ion chromatography].

    PubMed

    Yu, Ruipeng; Hu, Zhongyang; Ye, Mingli; Che, Jinshui

    2012-04-01

    A method based on accelerated solvent extraction-ion chromatography (ASE-IC) was developed for the simultaneous determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in plastic samples. The accelerated solvent extraction was employed as the pretreatment method for the simultaneous extraction of the Cr(III) and Cr(VI) from the samples. Cr(III) and Cr(VI) were derivatized with 2,6-pyridinedicarboxylic acid (PDCA) and 1,5-diphenyl-carbazide (DPC), and detected by an ultraviolet-visible (UV-Vis) detector at UV and visible wavelengths, respectively. The results showed that the limits of detection for Cr(III) and Cr(VI) were 5.0 microg/L and 0.5 microg/L and the good linearities of the calibration curves for them were in the ranges of 50 - 1 000 microg/L (r2 = 0.9994) and 5.0 - 100 microg/L (r2 = 0.9998), respectively. The recoveries were between 90.7% and 101.1% with the relative standard deviations (RSDs) of 1.7% -4.4% for Cr(III) and Cr(VI). The method is sensitive, reproducible and adaptable to the simultaneous determination of Cr(III) and Cr(VI) in the plastic samples.

  20. Extraction of chromium(III) and chromium(VI) species from solid matrices using green solvent supercritical carbon dioxide.

    PubMed

    Wang, Joanna Shaofen; Chiu, Kong-Hwa

    2007-11-01

    Supercritical fluid extraction (SFE) provides an environmentally green technique to decontaminate chromium species from solid matrices using supercritical fluid carbon dioxide (ScCO2). Methanol and a small amount of water were found to significantly improve the extraction efficiency. The fluorinated chelating agent lithium bis(trifluoroethyl)-dithiocarbamate (LiFDDC) was effective in removing Cr ions in methanol-modified CO2 via in situ chelation/SFE technique. This paper indicates that the extraction efficiencies of Cr(III) and Cr(VI) from solid matrices can be greatly increased to more than 92% in the presence of a small amount of water, using 5% methanol-modified CO2 containing LiFDDC as an extractant. Chromium species in a wood waste sample in the form of chromated copper arsenate (CCA) can be extracted, but the extraction efficiency is not as good as expected, possibly due to the complications of the chemistry of Cr species in different oxidation states and to matrix effects.