Separation of valence forms of chromium(III) and chromium(VI) by coprecipitation with iron(III) hydroxide

International Nuclear Information System (INIS)

Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

1989-01-01

The sorption of 9.62·10 -5 M of Cr (III) and Cr (VI) with iron hydroxide in 1 M potassium nitrate and potassium chloride was investigated in relation to the pH of the medium. Experimental data on the sorption of chromium(III) and chromium(VI) with iron(III) hydroxide made it possible to determine the region of practically complete concentration of Cr (III) and Cr (VI) (pH = 3-6.5). The results from spectrophotometric investigations, calculated data on the distribution of the hydroxocationic forms of chromium(III) and the anions of chromium(IV), and their sorption by iron-(III) hydroxide made it possible to characterize the sorbability of the cationic and anionic forms of chromium in various degrees of oxidation. On this basis a method was developed for the separation of chromium(III) and chromium(VI) by coprecipitation on iron(III) hydroxide and their separation from the iron(III) hydroxide support

Chromium base high performance materials: Where and how do they come from?

Science.gov (United States)

Choi, In-Kap

1996-08-01

The origin of chromium base performance materials (CBPM) is described. CBPM may include (1) trivalent chromium chemicals such as chromic acetate, chromic chloride, chromic bromide, chromic fluoride, chromic iodide, chromic phosphate, and chromic sulfate; (2) hexavalent chromium chemicals such as chromic acid, lithium chromate, sodium chromate, sodium dichromate, and potassium dichromate; (3) oxide forms of chromium such as black chrome, chromium dioxide, chromium oxide, and chromium hydroxide; and (4) other chromium compounds such as chromium aluminide, chromium boride, chromium carbide, chromium molybdate, chromium nitride, chromium silicide, chromium tungstate and lanthanum chromite. Extensive reviews of production processes, properties, and applications/end uses of CBPM are made.

Substoichiometric extraction of chromium

International Nuclear Information System (INIS)

Shigematsu, T.; Kudo, K.

1980-01-01

Substoichiometric extraction of chromium with tetraphenylarsonium chloride (TPACl), tri-n-octylamine (TNOA), diethylammonium diethyldithiocarbamate (DDDC) and ammonium pyrrolidinedithiocarbamate (APDC) was examined in detail. Chromium can be extracted substoichiometrically in a pH range, which is 1.1-2.6 for the TPACl compound, 0.6-2.3 for the TNOA compound, 5.1-6.4 for the DDDC chelate and 3.9-4.9 for the APDC chelate. Chromium in high-purity calcium carbonate, Orchard Leaves (NBS SRM-1571) and Brewers Yeast (NBS SRM-1569) was determined by neutron activation analysis combined with substoichiometric extraction by DDDC and APDC. The values of 2.0+-0.02 ppm and 2.6+-0.2 ppm were obtained for Brewers Yeast and Orchard Leaves, respectively. These values were in good agreement with those reported by NBS. The reaction mechanism and the reaction ratio between hexavalent chromium and dithiocarbamate are also discussed. (author)

Nanomagnetic domains of chromium deposited on vertically-aligned carbon nanotubes

International Nuclear Information System (INIS)

Wright, Andrew C.; Faulkner, Michael K.; Harris, Robert C.; Goddard, Alex; Abbott, Andrew P.

2012-01-01

The drive to create ever smaller magnetic memory devices has led to the development of new nanomagnetic domains on surfaces. This paper reports the development of nano-chromium magnetic domains obtained using electrodeposition on vertically aligned carbon nanofibers arrays. Attempts to achieve this using conventional aqueous solutions were unsuccessful even after thin nickel underlayers were applied. The use of a novel electrolyte, a deep eutectic solvent, made from choline chloride: chromium (III) chloride enabled highly conformal overcoatings of chromium on individual bare carbon nanotubes to be obtained. Very high aspect ratio metal microstructures could be obtained by this novel technology. Magnetic imaging of the coated nanoarrays showed there to be clear magnetic character to the coating when the thin coatings were applied but this disappeared when the deposits were thicker and more contiguous. - Highlights: ► Nanoscale chromium deposited from non-aqueous electrolyte shows magnetic behavior. ► Vertically aligned carbon nanotubes conformally coated with chromium metal. ► Ionic liquid electrolyte superior to chromic acid for plating high aspect ratio structures.

Nanomagnetic domains of chromium deposited on vertically-aligned carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Wright, Andrew C., E-mail: a.wright@glyndwr.ac.uk [Advanced Materials Research Laboratory, Materials Science Research Center, Glyndwr University, Wrexham LL11 2AW (United Kingdom); Faulkner, Michael K., E-mail: m.faulkner@manchester.ac.uk [Manchester Materials Science Centre, University of Manchester, Grosvenor Street, Manchester M13 9PL (United Kingdom); Harris, Robert C.; Goddard, Alex; Abbott, Andrew P., E-mail: apa1@le.ac.uk [Department of Chemistry, University of Leicester, Leicester LE1 7RH (United Kingdom)

2012-12-15

The drive to create ever smaller magnetic memory devices has led to the development of new nanomagnetic domains on surfaces. This paper reports the development of nano-chromium magnetic domains obtained using electrodeposition on vertically aligned carbon nanofibers arrays. Attempts to achieve this using conventional aqueous solutions were unsuccessful even after thin nickel underlayers were applied. The use of a novel electrolyte, a deep eutectic solvent, made from choline chloride: chromium (III) chloride enabled highly conformal overcoatings of chromium on individual bare carbon nanotubes to be obtained. Very high aspect ratio metal microstructures could be obtained by this novel technology. Magnetic imaging of the coated nanoarrays showed there to be clear magnetic character to the coating when the thin coatings were applied but this disappeared when the deposits were thicker and more contiguous. - Highlights: Black-Right-Pointing-Pointer Nanoscale chromium deposited from non-aqueous electrolyte shows magnetic behavior. Black-Right-Pointing-Pointer Vertically aligned carbon nanotubes conformally coated with chromium metal. Black-Right-Pointing-Pointer Ionic liquid electrolyte superior to chromic acid for plating high aspect ratio structures.

Permeation of chromium salts through human skin in vitro

DEFF Research Database (Denmark)

Gammelgaard, Bente; Fullerton, A; Avnstorp, C

1992-01-01

Chromium permeation studies were performed on full thickness human skin in diffusion cells. All samples were analysed for the total chromium content by graphite furnace Zeeman-corrected atomic absorption spectrometry. Some samples were analysed by an ion chromatographic method permitting...... the simultaneous determination of Cr(VI) and Cr(III) as well. The amounts of chromium found in all skin layers were significantly higher when potassium dichromate was applied to the skin compared with chromium chloride or chromium nitrate. Chromium could only be detected in the recipient phase after application...... of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...

Effect of metal chloride solutions on coloration and biaxial flexural strength of yttria-stabilized zirconia

Science.gov (United States)

Oh, Gye-Jeong; Lee, Kwangmin; Lee, Doh-Jae; Lim, Hyun-Pil; Yun, Kwi-Dug; Ban, Jae-Sam; Lee, Kyung-Ku; Fisher, John G.; Park, Sang-Won

2012-10-01

The effect of three kinds of transition metal dopants on the color and biaxial flexural strength of zirconia ceramics for dental applications was evaluated. Presintered zirconia discs were colored through immersion in aqueous chromium, molybdenum and vanadium chloride solutions and then sintered at 1450 °C. The color of the doped specimens was measured using a digital spectrophotometer. For biaxial flexural strength measurements, specimens infiltrated with 0.3 wt% of each aqueous chloride solution were used. Uncolored discs were used as a control. Zirconia specimens infiltrated with chromium, molybdenum and vanadium chloride solutions were dark brown, light yellow and dark yellow, respectively. CIE L*, a*, and b* values of all the chromium-doped specimens and the specimens infiltrated with 0.1 wt% molybdenum chloride solution were in the range of values for natural teeth. The biaxial flexural strengths of the three kinds of metal chloride groups were similar to the uncolored group. These results suggest that chromium and molybdenum dopants can be used as colorants to fabricate tooth colored zirconia ceramic restorations.

Chlorides retention of barium and chromium in two mangrove species Avicennia germinans and Rhizophora mangrove, developed in waters of the oil industry production, by means of the technique of hydroponics cultivation

International Nuclear Information System (INIS)

Grosso, J L; Sanchez L E; Avendano D; Restrepo, R

2000-01-01

The objective of the present study was to determine the phytoremediation mechanism (phytoextraction y/o rhizofiltration) given by the mangroves Rhizophora mangle and Avicennia germinans, when exposed to waters from an oil production field applying the hidroponia technique like system for growing the species. Determination of chlorides, barium and chromium bioaccumulation in tissues of mangrove species under study was compared with content of these elements in an inert substrate without mangroves. Bioaccumulation of the targeted elements was measured after 308 days exposure of the mangroves to production waters with initial barium and chromium contents of 1.25 g.m -3 and 0.002 g.m -3 respectively, and salinity in the range of 2,000 to 3,000 mg.kg -1 . Bioaccumulation of the studied elements (chlorides, barium and chromium) in tissues of both species was correlated to the increment in biomass of each species, as well as to the general physical condition of the plants. Survival rates higher than 95% of the exposed plants to production water during the time of study, increment in biomass of up to 5.88 g.day -1 , and concentrations of chlorides in tissues in the 0 - 170,000 mg.kg -1 during the considered period were observed. No significant difference between the two mangrove species was obtained. Bioaccumulation in tissues does not cause symptoms of deficiency in growing rates in the studied plants compared to natural rate indexes. Similarly, the analyses of inert substrate around the mangrove roots showed chloride and barium concentrations, contrary to the results of the targeted elements in the inert substrate when mangroves are not present. Both phytoremediation mechanisms were observed for the two mangrove species

RECOVERY OF COPPER(II AND CHROMIUM(III FROM NITRATE MEDIUM WITH SALICYLIDENEANILINE DISSOLVED IN 1-OCTANOL

Directory of Open Access Journals (Sweden)

A. Guerdouh

2016-05-01

Full Text Available The solvent extraction of copper(II and chromium(III from nitrate medium with salicylideneaniline (HL is studied as a function of various parameters: pH, concentration of salicylideneaniline, contact time and the nature of anoin (nitrate and sulfate in aqueous phase. Chromium(III is not extracted by salicylideneaniline  diluted in 1-octanol. Copper(II is only extracted by salicylideneaniline and it was found that the highest extractability achieved to 95% at pH 4.9, The stoichiometry of the extracted species was determined by using the method of slope analysis. Elemental analysis, UV–vis and IR-spectra were used to confirm the structure. It is found that the copper (II is extracted as CuL2.2H2O Their equilibrium constant, distribution coefficient, percentage extraction (%E and free energy are also calculated.

Calculated electronic structure of chromium surfaces and chromium monolayers on iron

International Nuclear Information System (INIS)

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

1985-01-01

A self-consistent calculation of the magnetic and electronic properties of the chromium (100) and (110) surfaces and of a chromium monolayer on the (100) and (110) iron surfaces is presented. It is found that (i) the (100) chromium surface is ferromagnetic with a greatly enhanced spin polarization (3.00 electrons); (ii) a substantial enhancement of the spin imbalance exists several (>5) layers into the bulk; (iii) the (110) chromium surface is antiferromagnetic with a large (2.31) spin imbalance; (iv) the (100) chromium monolayer on ferromagnetic iron is ferromagnetic, with a huge spin imbalance (3.63), and aligned antiferromagnetically with respect to the bulk iron; (v) the (110) chromium monolayer on ferromagnetic iron is also ferromagnetic, with a spin imbalance of 2.25 and antiferromagnetically aligned to the iron. The spin imbalance of chromium on iron (100) is possibly the largest of any transition-metal system

Synthesis, spectroscopic and thermal studies of the copper(II) aspartame chloride complex

Science.gov (United States)

Çakır, S.; Coşkun, E.; Naumov, P.; Biçer, E.; Bulut, İ.; İçbudak, H.; Çakır, O.

2002-08-01

Aspartame adduct of copper(II) chloride Cu(Asp) 2Cl 2·2H 2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions.

Experimental patch testing with chromium-coated materials.

Science.gov (United States)

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

2017-06-01

Chromium coatings on metal alloys can be decorative, and prevent corrosion and metal ion release. We recently showed that handling of a chromium-containing disc resulted in chromium deposition on the skin. To examine patch test reactivity to chromium-coated discs. We included 15 patients: 10 chromium-allergic patients, and 5 patients without chromium allergy. All were patch tested with potassium dichromate, cobalt chloride, nickel sulfate, and nine different metallic discs. The chromium-allergic patients were also patch tested with serial dilutions of potassium dichromate. Positive/weaker reactions were observed to disc B (1 of 10), disc C (1 of 10), and disc D, disc E, and disc I (4 of 10 each). As no controls reacted to any of the discs, the weak reactions indicate allergic reactions. Positive patch test reactions to 1770 ppm chromium(VI) in the serial dilutions of potassium dichromate were observed in 7 of 10 patients. When the case group was narrowed down to include only the patients with a current positive patch test reaction to potassium dichromate, elicitation of dermatitis by both chromium(III) and chromium(VI) discs was observed in 4 of 7 of patients. Many of the patients reacted to both chromium(III) and chromium(VI) surfaces. Our results indicate that both chromium(VI) and chromium(III) pose a risk to chromium-allergic patients. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Study of the polarization for Incoloy 800 and for the stainless stell AISI 304 in mixtures of Iron, Nickel and Chromium Chlorides

International Nuclear Information System (INIS)

Travalloni, A.M.; Sathler, L.; Mattos, O.R.

1985-01-01

Polarization curves for the Incoloy 800 and for the stainless stell AISI 304 were obtained with static and rotational electrodes. The electrolytes employed showed growing concentrations of mixtures as Iron, Nickel and Chromium Chlorides their proportion being the same as the content of these elements in the respective alloys. The alloys under investigation exhibited a continuous transition behaviour from the passive to the active-passive and to the active conditions. Also, the pH was found the main parameter controlling the anodic behaviour of the alloy. (Author) [pt

Chromium, Nickel and Zinc Induced Histopathological Alterations in ...

African Journals Online (AJOL)

Michael Horsfall

fish, Labeo rohita to chlorides of chromium, nickel and zinc for 30 days. However ... toxicants such as salts of heavy metals, acids, organic matter ... nutritional supply becomes excessive. ... action), petrochemicals, and fertilizers and in steam.

Mechanistic insight into chromium(VI) reduction by oxalic acid in the presence of manganese(II)

Energy Technology Data Exchange (ETDEWEB)

Wrobel, Katarzyna; Corrales Escobosa, Alma Rosa; Gonzalez Ibarra, Alan Alexander; Mendez Garcia, Manuel; Yanez Barrientos, Eunice; Wrobel, Kazimierz, E-mail: kazimier@ugto.mx

2015-12-30

Over the past few decades, reduction of hexavalent chromium (Cr(VI)) has been studied in many physicochemical contexts. In this research, we reveal the mechanism underlying the favorable effect of Mn(II) observed during Cr(VI) reduction by oxalic acid using liquid chromatography with spectrophotometric diode array detector (HPLC–DAD), nitrogen microwave plasma atomic emission spectrometry (HPLC–MP-AES), and high resolution mass spectrometry (ESI–QTOFMS). Both reaction mixtures contained potassium dichromate (0.67 mM Cr(VI)) and oxalic acid (13.3 mM), pH 3, one reaction mixture contained manganese sulfate (0.33 mM Mn(II)). In the absence of Mn(II) only trace amounts of reaction intermediates were generated, most likely in the following pathways: (1) Cr(VI) → Cr(IV) and (2) Cr(VI) + Cr(IV) → 2Cr(V). In the presence of Mn(II), the active reducing species appeared to be Mn(II) bis-oxalato complex (J); the proposed reaction mechanism involves a one-electron transfer from J to any chromium compound containing Cr=O bond, which is reduced to Cr−OH, and the generation of Mn(III) bis-oxalato complex (K). Conversion of K to J was observed, confirming the catalytic role of Mn(II). Since no additional acidification was required, the results obtained in this study may be helpful in designing a new, environmentally friendly strategy for the remediation of environments contaminated with Cr(VI).

EFFECTS OF HIGHER LEVELS OF CHROMIUM AND COPPER ON SOME HAEMATOLOGICAL PARAMETERS AND SERUM PROTEINS IN BROILERS

Directory of Open Access Journals (Sweden)

M. Tariq Javed, F, Ahmad. N, Z, Rafique1 and M, Bashir

2003-01-01

Full Text Available Effects of higher levels of chromium alone and in combination with copper were investigated in broiler chicks divided into seven equal groups viz. A, B, C, D, E, F and G. Group G served as control receiving no treatment. Groups A, B and F received chromium chloride at the rate of 2 g/kg and nicotinic acid 150 mg/kg feed while C, D and F received chromium chloride 8 g/kg and nicotinic acid 150mg/kg. Broilers of groups A and C received copper sulfate at the rate of 200 mg/kg while groups Band D 400 mg/kg feed. Haematological parameters studied revealed non-significant difference between treatment groups and control in haemoglobin concentration and total erythrocyte counts. However, only at 4th week, lower PCV was observed in birds fed higher levels of chromium chloride alone. Increase in TLC was observed in birds fed low chromium alone or' with low levels of copper. Results of serum proteins including total protein, albumin and globulin during first three weeks showed significantly or relatively lower values in treatment groups than control. Serum globulins generally revealed non-significant difference between treatment groups and control.

Sorption of chromium(VI) and chromium(III) on aluminium hydroxide

International Nuclear Information System (INIS)

Music, S.

1986-01-01

Factors that influence the sorption of Cr(VI) and Cr(III) on aluminium hydroxide were investigated. The sorption of chromates decreases as the pH of the suspension increases. The mechanism of CrOsub(4)sup(2-) sorption was interpreted in terms of reactions between chromates and -OH and/or Hsub(2)O groups at the hydroxide/liquid interface. It was shown that chromates are more tightly sorbed on aluminium hydroxide compared to other anions, e.g. chlorides. On the other hand, specifically absorbed anions, such as molybdates, compete strongly with chromates for the sorption sites. The sorption of chromium(III) increases with the pH of the suspension. Also, the sorption of chromium(III) is suppressed in the presence of citrate ions. The best conditions for the fixation of Cr(VI) and Cr(III) by aluminium hydroxide are presented. (author)

Electrochemistry of vanadium(II and the electrodeposition of aluminum-vanadium alloys in the aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt

Directory of Open Access Journals (Sweden)

Tsuda T.

2003-01-01

Full Text Available The electrochemical behavior of vanadium(II was examined in the 66.7-33.3 mole percent aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt containing dissolved VCl2 at 353 K. Voltammetry experiments revealed that V(II could be electrochemically oxidized to V(III and V(IV. However at slow scan rates the V(II/V(III electrode reaction is complicated by the rapid precipitation of V(III as VCl3. The reduction of V(II occurs at potentials considerably negative of the Al(III/Al electrode reaction, and Al-V alloys cannot be electrodeposited from this melt. However electrodeposition experiments conducted in VCl2-saturated melt containing the additive, 1-ethyl-3-methylimidazolium tetrafluoroborate, resulted in Al-V alloys. The vanadium content of these alloys increased with increasing cathodic current density or more negative applied potentials. X-ray analysis of Al-V alloys that were electrodeposited on a rotating copper wire substrate indicated that these alloys did not form or contain an intermetallic compound, but were non-equilibrium or metastable solid solutions. The chloride-pitting corrosion properties of these alloys were examined in aqueous NaCl by using potentiodynamic polarization techniques. Alloys containing ~10 a/o vanadium exhibited a pitting potential that was 0.3 V positive of that for pure aluminum.

Kinetics of chromium (VI) reduction by ferrous iron

International Nuclear Information System (INIS)

Batchelor, B.; Schlautman, M.; Hwang, I.; Wang, R.

1998-09-01

Chromium is a primary inorganic contaminant of concern at the Pantex Plant. Chromium concentrations have been found to be two orders of magnitude higher than the drinking water standards, particularly in certain wells in the perched aquifer below Zone 12. In situ reduction of a mobile form of chromium, Cr(VI) to an immobile form, Cr(III), was examined as a viable option to active soil restoration. Successfully immobilizing chromium in the vadose zone as Cr(III) will reduce the amount of chromium that reaches the groundwater table. The results from the solution experiments indicated that chromium was rapidly and stoichiometrically reduced by Fe(II) in solution. Also, the slurry experiments showed that the aquifer solids removed Fe(II) from solution, but a portion of the iron removed remained available for reaction with Cr(VI), but at a slower rate. A model to predict different amounts of iron pseudo-components was developed, which allowed prediction of iron amounts required to reduce chromium under in situ conditions

Fractionation of chromium(III) compounds in biological matrices

Energy Technology Data Exchange (ETDEWEB)

Knoechel, A.; Weseloh, G. [Institute of Inorganic and Applied Chemistry, University of Hamburg (Germany)

1999-03-01

Many details of the metabolism and biological significance of trivalent inorganic cations have remained obscure up to now, not least because of the lack of appropriate tools for species analysis of these cations in biological matrices. In order to demonstrate the capabilities of reversed-phase ion-pair chromatography, the distribution of chromium species in brewer`s yeast, previously incubated with radiolabelled {sup 51}Cr chloride was investigated. Contradictory to the findings of most other researchers in this area, two low-molecular weight, anionic chromium species were detected in cytosolic yeast extracts. In conclusion, reversed-phase ion-pair chromatography may reveal new details of intracellular metabolism of chromium(III) and, possibly, other trivalent cations. (orig.) With 1 fig., 16 refs.

Synthesis and spectral properties of Chromium(III) complex of ...

African Journals Online (AJOL)

ISSCH) with chromium(III) chloride. The complex was characterized by molar conductance, magnetic moment, infrared, far-infrared and electronic spectra and elemental analysis. The ligand exists in keto tantomeric form and it coordinates through ...

EXTENDED ANALYSIS OF THE SPECTRUM OF SINGLY IONIZED CHROMIUM (Cr II)

Energy Technology Data Exchange (ETDEWEB)

Sansonetti, Craig J.; Nave, Gillian [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

2014-08-01

We have made new observations of the spectrum of singly ionized chromium (Cr II) in the region 2850-37900 Å with the National Institute of Standards and Technology 2 m Fourier transform spectrometer. These data extend our previously reported observations in the near-ultra-violet region. We present a comprehensive list of more than 5300 Cr II lines classified as transitions among 456 even and 457 odd levels, 179 of which are newly located in this work. Using highly excited levels of the 3d {sup 4}({sup 5} D)5g, 3d {sup 4}({sup 5} D)6g, and 3d {sup 4}({sup 5}D)6h configurations, we derive an improved ionization energy of 132971.02 ± 0.12 cm{sup –1} (16.486305 ± 0.000015 eV)

Filtrates & Residues: Experimental Work with Tin (II) Chloride in a High School.

Science.gov (United States)

Sanchez, Manuela Martin

1988-01-01

Presents a high school chemistry lab experiment using tin (II) chloride to explore the concepts of hydrolysis, Le Chatelier's principle, and electrolysis. Presents methodology and the chemistry involved. Offers questions for the students. (MVL)

Determination of Chromium(III) Picolinate Using High Performance Liquid Chromatography-Ultraviolet Spectrophotometry

International Nuclear Information System (INIS)

Kim, Sung Il; Woo, Dong Jin; Kang, Dae Kyung; Lee, Myung Hee; Woo, Gun Jo; Cha, Ki Won

2003-01-01

Cr-(pic) 3 has been widely used as food additives, drugs, and feed additives. Accordingly, its determination method should be established. In the present paper, we have studied the determination method of chromium(III) picolinate accurately using ESI-MS on-lined with HPLC. Chromium(III) picolinate in feed products was determined successfully. Chromium(III) is very well known as an essential mineral. It is suggested as a cofactor in the maintenance of both normal lipid and carbohydrate metabolism by assisting the action of insulin on a cell membrane. According to the National Research Council, the daily recommended intake of chromium(III) is 50-200 μg. Several organic chromium(III) complexes have been reported to have significantly higher absorption and tissue incorporation activity than inorganic salts such as chromium(III) chloride

Rhenium corrosion in chloride melts

International Nuclear Information System (INIS)

Stepanov, A.D.; Shkol'nikov, S.N.; Vetyukov, M.M.

1989-01-01

The results investigating rhenium corrosion in chloride melts containing sodium, potassium and chromium ions by a gravimetry potentials in argon atmosphere in a sealing quarth cell are described. Rhenium corrosion is shown to be rather considerable in melts containing CrCl 2 . The value of corrosion rate depending on temperature is determined

40 CFR Appendix III to Part 266 - Tier II Emission Rate Screening Limits for Free Chlorine and Hydrogen Chloride

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Tier II Emission Rate Screening Limits for Free Chlorine and Hydrogen Chloride III Appendix III to Part 266 Protection of Environment... to Part 266—Tier II Emission Rate Screening Limits for Free Chlorine and Hydrogen Chloride Terrain...

Direct synthesis of ligand-based radicals by the addition of bipyridine to chromium(II) compounds.

Science.gov (United States)

Zhou, Wen; Desnoyer, Addison N; Bailey, James A; Patrick, Brian O; Smith, Kevin M

2013-03-04

The reaction of 2,2'-bipyridine (bpy) with monomeric chromium(II) precursors was used to prepare the S = 1 complexes Cr(tBu-acac)2(bpy) (1) and (η(5)-Cp)(η(1)-Cp)Cr(bpy) (3), as well as the S = 2 compound Cr[N(SiMe3)2]2(bpy) (4). The crystallographically determined bond lengths indicate that the bpy ligands in 1 and 3 are best regarded as radical anions, while 4 shows no structural evidence for electron transfer from Cr(II) to the neutral bpy ligand.

Trivalent Chromium Process (TCP) as a Sealer for MIL-A-8625F Type II, IIB, and IC Anodic Coatings

National Research Council Canada - National Science Library

Matzdorf, Craig; Beck, Erin; Hilgeman, Amy; Prado, Ruben

2008-01-01

This report documents evaluations of trivalent chromium compositions (TCP) as sealers for MIL-A-8625F Type II, IIB, and IC anodic coatings conducted from March 2001 through December 2007 by Materials Engineering...

Reducing elution in anion exchange chromatography as a pretreatment of colorimetry of chromium(VI) and vanadium(V)

International Nuclear Information System (INIS)

Shigetomi, Yasumasa; Hatamoto, Takeji; Nagoshi, Kimie; Yamashige, Takashi.

1976-01-01

In order to increase the selectivity of the colorimetry of chromium and vanadium, the separation by means of anion exchange chromatography was tested. The column, phi 0.8x5.0 cm packing (50--100 mesh) Dowex 1x4 anion exchange resin was used for the separation of chromium. The solution containing chromium (VI), zinc(II), cadmium(II), iron(III) and reducing organic substances contained in industrial waste water was introduced into the column and then the substances other than chromium(VI) were removed by washing the column with distilled water. Finally chromium(VI) was reduced to chromium(III) by hydroxylamine in the eluent and eluted. The concentration of sulfuric acid and hydroxylamine in the eluent were 0.1 mol/l and 0.001 mol/l respectively. For analyzing chromium(III) in the mixture of chromium(VI) and chromium(III), after removal of chromium(VI) it should be oxidized to chromium(VI) anion with the oxidant, e.g., sodium peroxide or hydrogen peroxide, before introducing it into the column. In terms of the pretreatment by using the acetate form resin column, chromium (VI) and chromium(III) can be determined separately in the solution whose concentration ranges from 0.05 ppm to 0.5 ppm despite the presence of contaminants, which interfere with the colorimetric determination of chromium(VI) using diphenylcarbonohydrazide, in the original solution. The separation of vanadium(V) in the solution containing copper(II), cobalt(II) and etc. was made using the mixed solution of hydrochloric acid (2 mol/l) and hydroxylamine (0.2 mol/l) similarly to chromium(VI). In terms of the similar pretreatment vanadium could be determined precisely as far as 0.1 ppm by the colorimetry using 4-(2-pyridylazo) resorcinol despite the presence of copper(II), cobalt(II), nickel(II) and etc in the original solution. (auth.)

Behaviour of carbon steel and chromium steels in CO2 environments

International Nuclear Information System (INIS)

Lefebvre, B.; Bounie, P.; Guntz, G.; Prouheze, J.C.; Renault, J.J.

1984-01-01

The behavior in aqueous CO 2 environments of steel with chromium content between 0 and 22% has been studied by autoclave tests. The influence of chromium and molybdenum contents has been investigated particularly on 13 Cr steel. Conventional electrochemical test results are related to the CO 2 autoclave test results. The influence of the environment: temperature, chloride concentration, partial pressure of CO 2 and some amount of H 2 S on the corrosion resistance are discussed

Predicting chromium (VI) adsorption rate in the treatment of liquid ...

African Journals Online (AJOL)

Administrator

The adsorption rate of chromium (VI) on commercial activated carbon during the ... time and initial chromium (VI) ion concentration. .... model, the separation factor r, according to Calvo et al (2001) cited .... Lead (II) and nickel (II) adsorption kinetics .... heavy metal by Talaromyces helicus: a trained fungus for copper and.

REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

Directory of Open Access Journals (Sweden)

A. R. Asgari ، F. Vaezi ، S. Nasseri ، O. Dördelmann ، A. H. Mahvi ، E. Dehghani Fard

2008-10-01

Full Text Available Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide. It was found that granular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from water at pH≤7 and in 90 min contact time. Maximum adsorption capacity was determined to be 0.788 mg Cr+6/g granular ferric hydroxide. Although relatively good adsorption of sulfate and chloride had been specified in this study, the interfering effects of these two anions had not been detected in concentrations of 200 and 400 mg/L. The absorbability of hexavalent chromium by granular ferric hydroxide could be expressed by Freundlich isotherm with R2>0.968. However, the disadvantage was that the iron concentration in water was increased by the granular ferric hydroxide. Nevertheless, granular ferric hydroxide is a promising adsorbent for chromium removal, even in the presence of other interfering compounds, because granular ferric hydroxide treatment can easily be accomplished and removal of excess iron is a simple practice for conventional water treatment plants. Thus, this method could be regarded as a safe and convenient solution to the problem of chromium-polluted water resources.

Hexavalent Chromium reduction by Trichoderma inhamatum

Energy Technology Data Exchange (ETDEWEB)

Morales-Battera, L.; Cristiani-Urbina, E.

2009-07-01

Reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] is a useful and attractive process for remediation of ecosystems and industrial effluents contaminated with Cr(VI). Cr(VI) reduction to Cr(II) can be achieved by both chemical and biological methods; however, the biological reduction is more convenient than the chemical one since costs are lower, and sludge is generated in smaller amounts. (Author)

Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiaolei; Dong, Hailiang; Yang, Xuewei; Kovarik, Libor; Chen, Yu; Zeng, Qiang

2018-02-01

Iron-bearing clay minerals and organic matter are two important components in natural environments that influence hexavalent chromium (Cr(VI)) reduction. Previous studies have shown that organic ligands could influence Cr(VI) reduction by aqueous Fe2+ and pyrite. However, the effects of organic ligands on Cr(VI) reduction by structural Fe(II) in clays are not well understood. In this study, the effects of citrate on Cr(VI) reduction by nontronite (NAu-2) were investigated under near neutral pH condition (pH=6). Our results showed that the presence of citrate decreased the rate but increased the amount of Cr(VI) reduction by structural Fe(II) in NAu-2. The decreased reaction rate was likely due to competitive sorption of citrate and polyanionic dichromate (Cr2O7- ), because sorption of dichromate appeared to be the first step for subsequent Cr(VI) reduction. The increased amount of Cr(VI) reduction in the presence of citrate was likely because citrate provided additional reducing power through ligand-metal electron transfer in the presence of soluble Fe 3+ derived from dissolution of reduced NAu-2. Soluble Cr(III)-citrate complex was the possible form of reduced chromium when citrate was present. In contrast, nanometer-sized Cr2O3 particles were the product of Cr(VI) reduction by reduced NAu-2 without citrate. Our study highlights the importance of organic ligands on Cr(VI) reduction and immobilization when iron-bearing clay minerals are applied to treat Cr(VI) contaminant in organic matter rich environments.

Crystal structures and DFT calculations of mixed chloride-azide zinc(II) and chloride-isocyanate cadmium(II) complexes with the condensation product of 2-quinolinecarboxaldehyde and Girard's T reagent

Science.gov (United States)

Anđelković, Katarina; Pevec, Andrej; Grubišić, Sonja; Turel, Iztok; Čobeljić, Božidar; Milenković, Milica R.; Keškić, Tanja; Radanović, Dušanka

2018-06-01

The mixed chloride-azide [ZnL(N3)1.65Cl0.35] (1) and chloride-isocyanate [CdL(NCO)1.64Cl0.36] (2) complexes with the condensation product of 2-quinolinecarboxaldehyde and trimethylammonium acetohydrazide chloride (Girard's T reagent) (HLCl) have been prepared and characterized by X-ray crystallography. In complexes 1 and 2, Zn1 and Cd1 ions, respectively, are five-coordinated in a distorted square based pyramidal geometry with NNO set of donor atoms of deprotonated hydrazone ligand and two monodentate ligands N3- and/or N3- and Cl- in the case of 1 and OCN- and/or OCN- and Cl- in the case of 2. The structural parameters of 1 and 2 have been discussed in relation to those of previously reported M(II) complexes with the same hydrazone ligand. Density functional theory calculations have been employed to study the interaction between the Zn2+ and Cd2+ ions and ligands. High affinity of ligands towards the Zn2+ and Cd2+ ions are predicted for both complexes.

Kinetics and Mechanism of Paracetamol Oxidation by Chromium(VI in Absence and Presence of Manganese(II and Sodiumdodecyl Sulphate

Directory of Open Access Journals (Sweden)

Maqsood Ahmad Malik

2007-11-01

Full Text Available The kinetics of paracetamol oxidation are first order each in [paracetamol] and [HClO4]. The kinetic study shows that the oxidation proceeds in two steps. The effects of anionic micelles of sodiumdodecyl sulphate (SDS and complexing agents (ethylenediammine tetraacetic acid (EDTA and 2,2′-bipyridyl (bpy were also studied. Fast kinetic spectrophotometric method has been described for the determination of paracetamol. The method is based on the catalytic effect of manganese(II on the oxidation of paracetamol by chromium(VI in the presence of HClO4 (= 0.23 mol dm−3. Optimum reaction time is 4 to 6 minutes at a temperature of 30∘C. The addition of manganese(II ions largely decreased the absorbance of chromium(VI at 350 nm. This reaction can be utilized for the determination of paracetamol in drugs.

Synthesis and Characterization of Chromium (III) Complexes with L-Glutamic Acid, Glycine and LCysteine

OpenAIRE

Kun Sri Budiasih; Chairil Anwar; Sri Juari Santosa; Hilda Ismail

2013-01-01

Some Chromium (III) complexes were synthesized with three amino acids: L Glutamic Acid, Glycine, and L-cysteine as the ligands, in order to provide a new supplement containing Cr(III) for patients with type 2 diabetes mellitus. The complexes have been prepared by refluxing a mixture of Chromium(III) chloride in aqueous solution with L-glutamic acid, Glycine, and L-cysteine after pH adjustment by sodium hydroxide. These complexes were characterized by Infrared and Uv-Vis s...

Interaction between gold (III) chloride and potassium hexacyanoferrate (II/III)-Does it lead to gold analogue of Prussian blue?

Energy Technology Data Exchange (ETDEWEB)

Harish, S. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India); Joseph, James, E-mail: jameskavlam@yahoo.com [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India); Phani, K.L.N. [Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630006, Tamilnadu (India)

2011-06-30

Highlights: > In group IB, Cu and Ag form Prussian blue analogues but similar formation of gold hexacyanoferrate was not found in the literature and non-existence of gold hexacyanoferrate remains a mystery. > Potential cycling of gold chloride and potassium ferro/ferri cyanide was resulted in the formation of Au-PB nano-composite. > Redox reaction between gold chloride and potassium ferrocyanide ion is spontaneous but no reaction occurs when gold chloride and potassium ferricyanide is mixed. > We are proposing the formation of a compound with general formula 'KFe{sub x}[Au(CN){sub 2}]{sub y}' and discussing the formation of gold hexacyanoferrate is not feasible by simple chemical or electrochemical reaction in contrast to other PB analogues. - Abstract: Prussian blue analogues are a class of compounds formed by the reaction between metal salt and potassium hexacyanoferrate (II/III). In our earlier report, the formation of Au-Prussian blue nano-composite was noticed on potential cycling the glassy carbon electrode in a medium containing gold (III) chloride and potassium hexacyanoferrate (III). Hence in this work, the formation of gold hexacyanoferrate was attempted by a simple chemical reaction. The reaction of gold (III) chloride with potassium hexacyanoferrate (II/III) was examined by UV-Vis spectroscopy and found that there is no redox reaction between gold (III) chloride and potassium hexacyanoferrate (III). However, the redox reaction occurs between gold (III) chloride and potassium hexacyanoferrate (II) leading to the formation of charge transfer band and the conversion of hexacyanoferrate (II) to hexacyanoferrate (III) was evidenced by the emergence of new absorption peaks in UV-Vis spectra. The oxidation state of gold in Au-Fe complex was found to be +1 from X-ray photoelectron spectroscopy. The stability of the Au-Fe complex was also studied by cyclic voltammetry. Cyclic voltammetric results indicated the presence of high spin iron in Au

Interaction between gold (III) chloride and potassium hexacyanoferrate (II/III)-Does it lead to gold analogue of Prussian blue?

International Nuclear Information System (INIS)

Harish, S.; Joseph, James; Phani, K.L.N.

2011-01-01

Highlights: → In group IB, Cu and Ag form Prussian blue analogues but similar formation of gold hexacyanoferrate was not found in the literature and non-existence of gold hexacyanoferrate remains a mystery. → Potential cycling of gold chloride and potassium ferro/ferri cyanide was resulted in the formation of Au-PB nano-composite. → Redox reaction between gold chloride and potassium ferrocyanide ion is spontaneous but no reaction occurs when gold chloride and potassium ferricyanide is mixed. → We are proposing the formation of a compound with general formula 'KFe x [Au(CN) 2 ] y ' and discussing the formation of gold hexacyanoferrate is not feasible by simple chemical or electrochemical reaction in contrast to other PB analogues. - Abstract: Prussian blue analogues are a class of compounds formed by the reaction between metal salt and potassium hexacyanoferrate (II/III). In our earlier report, the formation of Au-Prussian blue nano-composite was noticed on potential cycling the glassy carbon electrode in a medium containing gold (III) chloride and potassium hexacyanoferrate (III). Hence in this work, the formation of gold hexacyanoferrate was attempted by a simple chemical reaction. The reaction of gold (III) chloride with potassium hexacyanoferrate (II/III) was examined by UV-Vis spectroscopy and found that there is no redox reaction between gold (III) chloride and potassium hexacyanoferrate (III). However, the redox reaction occurs between gold (III) chloride and potassium hexacyanoferrate (II) leading to the formation of charge transfer band and the conversion of hexacyanoferrate (II) to hexacyanoferrate (III) was evidenced by the emergence of new absorption peaks in UV-Vis spectra. The oxidation state of gold in Au-Fe complex was found to be +1 from X-ray photoelectron spectroscopy. The stability of the Au-Fe complex was also studied by cyclic voltammetry. Cyclic voltammetric results indicated the presence of high spin iron in Au-Fe complex. Hence 'as

Effect of the Type of Surface Treatment and Cement on the Chloride Induced Corrosion of Galvanized Reinforcements

Science.gov (United States)

Tittarelli, Francesca; Mobili, Alessandra; Vicerè, Anna Maria; Roventi, Gabriella; Bellezze, Tiziano

2017-10-01

The effect of a new passivation treatment, obtained by immersion of the galvanized reinforcements in a trivalent chromium salts based solution, on the chlorides induced corrosion has been investigated. To investigate also the effect of cement alkalinity on corrosion behaviour of reinforcements, concretes manufactured with three different European cements were compared. The obtained results show that the alternative treatment based on hexavalent chromium-free baths forms effective protection layers on the galvanized rebar surfaces. The higher corrosion rates of zinc coating in concrete manufactured with Portland cement compared to those recorded for bars in concrete manufactured with pozzolanic cement depends strongly on the higher chloride content at the steel concrete interface.

Dietary chromium and nickel enhance UV-carcinogenesis in skin of hairless mice

International Nuclear Information System (INIS)

Uddin, Ahmed N.; Burns, Fredric J.; Rossman, Toby G.; Chen, Haobin; Kluz, Thomas; Costa, Max

2007-01-01

The skin cancer enhancing effect of chromium (in male mice) and nickel in UVR-irradiated female Skh1 mice was investigated. The dietary vitamin E and selenomethionine were tested for prevention of chromium-enhanced skin carcinogenesis. The mice were exposed to UVR (1.0 kJ/m 2 3x weekly) for 26 weeks either alone, or combined with 2.5 or 5.0 ppm potassium chromate, or with 20, 100 or 500 ppm nickel chloride in drinking water. Vitamin E or selenomethionine was added to the lab chow for 29 weeks beginning 3 weeks before the start of UVR exposure. Both chromium and nickel significantly increased the UVR-induced skin cancer yield in mice. In male Skh1 mice, UVR alone induced 1.9 ± 0.4 cancers/mouse, and 2.5 or 5.0 ppm potassium chromate added to drinking water increased the yields to 5.9 ± 0.8 and 8.6 ± 0.9 cancers/mouse, respectively. In female Skh1 mice, UVR alone induced 1.7 ± 0.4 cancers/mouse, and the addition of 20, 100 or 500 ppm nickel chloride increased the yields to 2.8 ± 0.9, 5.6 ± 0.7 and 4.2 ± 1.0 cancers/mouse, respectively. Neither vitamin E nor selenomethionine reduced the cancer yield enhancement by chromium. These results confirm that chromium and nickel, while not good skin carcinogens per se, are enhancers of UVR-induced skin cancers in Skh1 mice. Data also suggest that the enhancement of UVR-induced skin cancers by chromate may not be oxidatively mediated since the antioxidant vitamin E as well as selenomethionine, found to prevent arsenite-enhanced skin carcinogenesis, failed to suppress enhancement by chromate

Effect of hydrogen chloride on the corrosion of an FeCrAlY alloy in simulated coal gasifier atmospheres

Energy Technology Data Exchange (ETDEWEB)

Coley, K.S.; Rhoades-Brown, J.E.; Blick, K.

1989-03-01

An iron chromium aluminium yttrium steel was exposed to a simulated coal gasifier atmosphere containing 1000 ppm and 2200 ppm hydrogen chloride at 450/sup 0/C. Increasing hydrogen chloride content was found to accelerate reaction rates, and significantly alter the microstructure and composition of the corrosion product. Tentative explanations for these results, involving vapour phase transport of metal chlorides are proposed.

Radiographic scanning agent

International Nuclear Information System (INIS)

Tofe, A.J.

1976-01-01

A stable radiographic scanning agent on a sup(99m)Tc basis has been developed. The substance contains a pertechnetate reduction agent, tin(II)-chloride, chromium(II)-chloride, or iron(II)-sulphate, as well as an organospecific carrier and ascorbic acid or a pharmacologically admissible salt or ester of ascorbic acid. (VJ) [de

Spectrophotometric Analysis of the Kinetic of Pd(II Chloride Complex Ions Sorption Process from Diluted Aqua Solutions Using Commercially Available Activated Carbon

Directory of Open Access Journals (Sweden)

Wojnicki M.

2017-12-01

Full Text Available In this paper, results of adsorption kinetic studies of Pd(II chloride complex ions on activated carbon Organosrob 10 CO are presented. Spectorphotometrical method was applied to investigate the process. Kinetic model was proposed, and fundamental thermodynamic parameters were determined. Proposed kinetic model describes well observed phenomenon in the studied range of concentration of Pd(II chloride complex ions as well, as concentration of activated carbon.

Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

International Nuclear Information System (INIS)

Zazoua, A.; Zougar, S.; Kherrat, R.; Samar, M.H.; Jaffrezic-Renault, N.; Errachid, A.; Abbaci, A.

2006-01-01

This paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/loga Cr 6+ in the range of 10 -4 to 10 -2 M. The detection limit was found to be 10 -5 M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium

Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

Energy Technology Data Exchange (ETDEWEB)

Zazoua, A. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Zougar, S. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Kherrat, R. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Samar, M.H. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Jaffrezic-Renault, N. [CEGELY-UMR 5005 CNRS, Ecole centrale de Lyon, 69134 Ecully cedex (France)]. E-mail: Nicole.Jaffrezic@ec-lyon.fr; Errachid, A. [Center of Reference for Bioengineering in Catalonia (CREBEC), Laboratory of Nanobioengineering, Parc Cientific de Barcelona, Universidad de Barcelona C/ Josep Samitier 1-5, 08028 Barcelona (Spain); Abbaci, A. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria)

2006-03-15

This paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/loga {sub Cr{sup 6+}} in the range of 10{sup -4} to 10{sup -2} M. The detection limit was found to be 10{sup -5} M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium.

Passivation and corrosion behaviours of cobalt and cobalt-chromium-molybdenum alloy

International Nuclear Information System (INIS)

Metikos-Hukovic, M.; Babic, R.

2007-01-01

Passivation and corrosion behaviour of the cobalt and cobalt-base alloy Co30Cr6Mo was studied in a simulated physiological solution containing chloride and bicarbonate ions and with pH of 6.8. The oxido-reduction processes included solid state transformations occurring at the cobalt/electrolyte interface are interpreted using theories of surface electrochemistry. The dissolution of cobalt is significantly suppressed by alloying it with chromium and molybdenum, since the alloy exhibited 'chromium like' passivity. The structural and protective properties of passive oxide films formed spontaneously at the open circuit potential or during the anodic polarization were studied using electrochemical impedance spectroscopy in the wide frequency range

Adsorption Studies of Chromium(VI) on Activated Carbon Derived from Mangifera indica (Mango) Seed Shell

Science.gov (United States)

Mise, Shashikant; Patil, Trupti Nagendra

2015-09-01

The removal of chromium(VI) from synthetic sample by adsorption on activated carbon prepared from Mangifera indica (mango) seed shell have been carried out at room temperature 32 ± 1 °C. The removal of chromium(VI) from synthetic sample by adsorption on two types of activated carbon, physical activation and chemical activation (Calcium chloride and Sodium chloride), Impregnation Ratio's (IR) 0.25, 0.50, 0.75 for optimum time, optimum dosages and variation of pH were studied. It is observed that contact time differs for different carbons i.e. for physically and chemically activated carbons. The contact time decreases for chemically activated carbon compared to the physically activated carbon. It was observed that as dosage increases the adsorption increased along with the increase in impregnation ratio. It was also noted that as I.R. increases the surface area of Mangifera indica shell carbon increased. These dosage data were considered in the construction of isotherms and it was found that adsorption obeys Freundlich Isotherm and does not obey Langmuir Isotherm. The maximum removal of chromium (VI) was obtained in highly acidic medium at a pH of 1.50.

Standard test methods for pitting and crevice corrosion resistance of stainless steels and related alloys by use of ferric Chloride solution

CERN Document Server

American Society for Testing and Materials. Philadelphia

2003-01-01

1.1 These test methods cover procedures for the determination of the resistance of stainless steels and related alloys to pitting and crevice corrosion (see Terminology G 15) when exposed to oxidizing chloride environments. Six procedures are described and identified as Methods A, B, C, D, E, and F. 1.1.1 Method A—Ferric chloride pitting test. 1.1.2 Method B—Ferric chloride crevice test. 1.1.3 Method C—Critical pitting temperature test for nickel-base and chromium-bearing alloys. 1.1.4 Method D—Critical crevice temperature test for nickel-base and chromium-bearing alloys. 1.1.5 Method E—Critical pitting temperature test for stainless steels. 1.1.6 Method F—Critical crevice temperature test for stainless steels. 1.2 Method A is designed to determine the relative pitting resistance of stainless steels and nickel-base, chromium-bearing alloys, whereas Method B can be used for determining both the pitting and crevice corrosion resistance of these alloys. Methods C, D, E and F allow for a rankin...

Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

Science.gov (United States)

Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

2017-09-05

Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

Study of calcium chloride and calcium nitrate purification on inorganic sorbents

International Nuclear Information System (INIS)

Vasil'eva, L.V.; Knyazeva, A.N.; Fakeev, A.A.; Belyaeva, N.A.; Morozov, V.I.; Kucherova, V.V.

1986-01-01

Purification of calcium chloride and calcium nitrate from iron, chromium, manganese and cobalt impurities by sorption on some inorganic collectors are considered in this article. Study was conducted by means of radioactive-tracer technique at concurrent use of several γ-radioactive isotopes. As a collectors were used hydrated aluminium and zirconium oxides. Dependence of effectiveness of precipitation by collectors on ph-value of medium, quantity of collector, nature and concentration of components is studied. Optimal parameters of purification of calcium chloride and calcium nitrate are defined.

Electrochemical behavior of ruthenium (III), rhodium (III) and palladium (II) in 1-butyl-3-methylimidazolium chloride ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, M.; Venkatesan, K.A. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Srinivasan, T.G. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)], E-mail: tgs@igcar.gov.in; Vasudeva Rao, P.R. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2009-11-01

Electrochemical behavior of ruthenium (III), rhodium (III) and palladium (II) in 1-butyl-3-methylimidazolium chloride (bmimCl) and their ternary and binary solutions in bmimCl was studied at various working electrodes at 373 K by cyclic voltammetry and chronoamperometry. Ruthenium (III) chloride forms a stable solution with bmimCl and the cyclic voltammogram of ruthenium (III) in bmimCl recorded at glassy carbon electrode consisted of several redox waves due to the complex nature of ruthenium to exist in several oxidation states. Electrolysis of ruthenium (III) chloride in bmimCl at the cathodic limit of bmimCl (-1.8 V (vs. Pd)) did not result in ruthenium metal deposition. However, it was deposited from bmimPF{sub 6} and bmimNTf{sub 2} room temperature ionic liquids at -0.8 V (vs. Pd). The electrochemical behavior of ruthenium (III) in bmimCl in the presence of palladium (II) and rhodium (III) was studied by cyclic voltammetry. The presence of palladium (II) in bmimCl favors underpotential deposition of ruthenium metal. The nuclear loop at -0.5 V (vs. Pd) was observed in all solutions when palladium (II) co-existed with other two metal ions. Nucleation and growth of the metal on glassy carbon working electrode was investigated by chronoamperometry. The growth and decay of chronocurrents has been found to follow the instantaneous nucleation model with three-dimensional growth of nuclei.

Reduction of hexavalent chromium by ferrous iron: A process of chromium isotope fractionation and its relevance to natural environments

DEFF Research Database (Denmark)

Døssing, Lasse Nørbye; Dideriksen, Knud; Stipp, Susan Louise Svane

2011-01-01

Stable chromium (Cr) isotopes can be used as a tracer for changing redox conditions in modern marine systems and in the geological record. We have investigated isotope fractionation during reduction of Cr(VI)aq by Fe(II)aq. Reduction of Cr(VI)aq by Fe(II)aq in batch experiments leads to significant...

The chemical behavior of acidified chromium (3) solutions. B.S. Thesis

Science.gov (United States)

Terman, D. K.

1981-01-01

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)).

Complexo-potentiometric determination of mercury (II) in chlormerodrin and mercuric chloride labelled with radioactive mercury

International Nuclear Information System (INIS)

Duek, E.E.

1976-09-01

A method is described for determining the amount of mercury (II) in radioactively labelled chlormerodrin and mercuric chloride. By measuring the absolute activity in an ionization chamber, the specific activity is therefore immediately obtained. The determination of Hg (II) is based on a complexometric titration. Because of method characteristics and speed convenience, the end point is observed by means of a pH-meter. A comparison is made with a determination performed by detecting the end point with color-change indicators. The error is estimated, and the results are statistically interpreted. (author) [es

Ferrate treatment for removing chromium from high-level radioactive tank waste.

Science.gov (United States)

Sylvester, P; Rutherford, L A; Gonzalez-Martin, A; Kim, J; Rapko, B M; Lumetta, G J

2001-01-01

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. This method could be generally applicable to removing chromium from chromium-contaminated solids, when coupled with a subsequent reduction of the separated chromate back to chromium(III). The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(II) molar ratio, but the chromium removal tends to level out for Fe(VI)/ Cr(III) greaterthan 10. Increasingtemperature leadsto better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be disposed as low-activity waste.

Design and performance of chromium mist generator

Directory of Open Access Journals (Sweden)

Tirgar Aram

2006-01-01

Full Text Available Chromium mist generator is an essential tool for conducting researches and making science-based recommendations to evaluate air pollution and its control systems. The purpose of this research was to design and construct a homogenous chromium mist generator and the study of some effective factors including sampling height and distances between samplers in side-by-side sampling on chromium mist sampling method. A mist generator was constructed, using a chromium electroplating bath in pilot scale. Concentration of CrO3 and sulfuric acid in plating solution was 125 g L-1 and 1.25 g L-1, respectively. In order to create permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d was installed the bath overhead. Sixty holes were produced on the chamber in 3 rows (each 20. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and effective factors were studied via side-by-side air sampling method. So, 48 clusters of samples were collected on polyvinyl chloride (PVC filters housed in sampling cassettes. Cassettes were located in 35, 50, and 65 cm above the solution surface with less than 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed according to the NIOSH method 7600. According to the ANOVA test, no significant differences were observed between different sampling locations in side-by-side sampling (P=0.82 and between sampling heights and different samplers distances (P=0.86 and 0.86, respectively. However, there were notable differences between means of coefficient of variations (CV in various heights and distances. It is concluded that the most chromium mist homogeneity could be obtained at height 50 cm from the bath solution surface and samplers distance of < 7.5 cm.

Tin (II Chloride Catalyzed Esterification of High FFA Jatropha Oil: Experimental and Kinetics Study

Directory of Open Access Journals (Sweden)

Ratna Dewi Kusumaningtyas

2014-05-01

Full Text Available Biodiesel is one of the promising energy source alternatives to fossil fuel. To produce biodiesel in a more economical way, the employment of the low-cost feed stocks, such as non-edible oils with high free fatty acid (FFA, is necessary. Accordingly, the esterification reaction of FFA in vegetable oils plays an important role in the biodiesel production. In this work, esterification of FFA contained in Crude Jatropha Oil (CJO in the presence of tin (II chloride catalyst in a batch reactor has been carried out. The esterification reaction was conducted using methanol at the temperature of 40-60 °C for 4 hours. The effect of molar ratio of methanol to oil was studied in the range 15:1 to 120:1. The influence of catalyst loading was investigated in the range of 2.5 to 15% w/w oil. The optimum reaction conversion was obtained at 60 °C with the catalyst loading of 10% w/w oil and molar ratio of methanol to oil of 120:1. A pseudo-homogeneous reversible second order kinetic model for describing the esterification of FFA contained in CJO with methanol over tin (II chloride catalyst was developed based on the experimental data. The kinetic model can fit the data very well.

Pitting corrosion of Inconel 600 in chloride and sulfate solutions at low temperature

International Nuclear Information System (INIS)

Chang Mingyu; Yu Geping

1993-01-01

Pitting corrosion of Inconel 600 was examined in chloride and sulfate solutions through usage of potentiodynamic polarization techniques. The effects of chloride and sulfate concentration were investigated in the range of 0.0001 to 0.1 M. Increasing chloride concentrations resulted in active shifts of the pit nucleation potential. Immunity to pitting corrosion was evident at a chloride level below 0.005 M. Increasing sulfate concentrations resulted in improved pitting resistance of Inconel 600 in chloride solutions. Detrimental effects associated with pitting were evident with low-level sulfate being added to dilute chloride media. The density of pits increased with increasing chloride concentrations or temperature between room temperature and 70 C. Systematic trends for the depth of pits were not evident. The observations of pitting corrosion in open immersion were consistent with those in polarization methods. Corrosion products contained in the pits were enriched in nickel, chromium and iron with a small amount of titanium and silicon. The enrichment of chlorine or sulfur was still, however, not found. (orig.)

Standard Test Methods for Detecting Susceptibility to Intergranular Corrosion in Wrought, Nickel-Rich, Chromium-Bearing Alloys

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 These test methods cover two tests as follows: 1.1.1 Method A, Ferric Sulfate-Sulfuric Acid Test (Sections 3-10, inclusive)—This test method describes the procedure for conducting the boiling ferric sulfate—50 % sulfuric acid test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to intergranular corrosion (see Terminology G 15), which may be encountered in certain service environments. The uniform corrosion rate obtained by this test method, which is a function of minor variations in alloy composition, may easily mask the intergranular corrosion components of the overall corrosion rate on alloys N10276, N06022, N06059, and N06455. 1.1.2 Method B, Mixed Acid-Oxidizing Salt Test (Sections 11-18, inclusive)—This test method describes the procedure for conducting a boiling 23 % sulfuric + 1.2 % hydrochloric + 1 % ferric chloride + 1 % cupric chloride test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to display a step function increa...

Effect of chromium chloride supplementation on glucose tolerance and serum lipids including high-density lipoprotein of adult men.

Science.gov (United States)

Riales, R; Albrink, M J

1981-12-01

Chromium deficiency may cause insulin resistance, hyperinsulinemia, impaired glucose tolerance, and hyperlipidemia, recovered by chromium supplementation. The effect of chromium supplementation on serum lipids and glucose tolerance was tested in a double-blind 12-wk study of 23 healthy adult men aged 31 to 60 yr. Either 200 micrograms trivalent chromium in 5 ml water (Cr) or 5 ml plain water (W) was ingested daily 5 days each week. Half the subjects volunteered for glucose tolerance tests with insulin levels. At 12 wk high-density lipoprotein cholesterol increased in the Cr group from 35 to 39 mg/dl (p less than 0.05) but did not change in the water group (34 mg/dl). The largest increase in high-density lipoprotein cholesterol and decreases in insulin and glucose were found in those subjects having normal glucose levels together with elevated insulin levels at base-line. The data are thus consistent with the hypothesis that Cr supplementation raises high-density lipoprotein cholesterol and improves insulin sensitivity in those with evidence of insulin resistance but normal glucose tolerance.

Stress corrosion cracking of Inconel 600 in aqueous solutions at elevated temperature. Pt. II. Effects of chloride and sulphate ions on the electrochemical behaviour of Inconel 600

International Nuclear Information System (INIS)

Ashour, E.A.; Schneider, F.; Mummert, K.

1997-01-01

For pt.I see ibid., p.151-6, 1997. The influencing effects of temperature, potential and electrolyte composition on the electrochemical behaviour of Inconel 600 in aqueous solutions are presented. Considering these effects the connection between the data have been obtained from chemo-mechanical fracture investigation on CT-samples in Part I of this paper and pitting corrosion are discussed. The results have shown that chloride ions depassivate the surfaces of cracks locally and hinder the formation of a new protective oxide layer on the fracture surfaces. Furthermore, chloride promotes the dissolution of metal and initiates the cracking, respectively. The resulting crevice corrosion promotes an increase of hydrogen absorption by the metal. The increase of the hydrogen content of the metal influences the mechanical fracture behaviour. Contrary, sulphate ions inhibit the initiation of corrosion mainly due to a hinderance of chloride ions adsorption on active sites of the fracture surfaces. The initiation of localized corrosion in the crevice region may be stimulated by chromate ions formed by oxidation of chromium from the oxide layer or the base metal in oxygen containing solutions. (orig.)

EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II ADSORPTION

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Nuryono Nuryono

2010-06-01

Full Text Available In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl and sulfuric acid (H2SO4 on kinetics of Cd(II adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II in aqueous solution with various concentrations. The Cd(II adsorbed was determined by analyzing the rest of Cd(II in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I followed by reaction of reversible first order (step II. Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol.     Keywords: adsorption, cdmium, diatomaceous earth, kinetics.

Transition metal coordination chemistry ofN,N-bis(2-{pyrid-2-ylethyl})hydroxylamine.

Science.gov (United States)

Belock, Christopher W; Cetin, Anil; Barone, Natalie V; Ziegler, Christopher J

2008-08-18

Although directly relevant to metal mediated biological nitrification as well as the coordination chemistry of peroxide, the metal complexes of hydroxylamines and their functionalized variants remain largely unexplored. The chelating hydroxylamine ligand N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine can be readily generated via a solvent free reaction in high purity; however, the ligand is prone to decomposition which can hamper metal reaction. N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine forms stable complexes with chromium(III), manganese(II), nickel(II), and cadmium(II) ions, coordinating in a side-on mode in the case of chromium and via the nitrogen in the case of the latter three metal ions. The hydroxylamine ligand can also be reduced to form N,N-bis(2-{pyrid-2-ylethyl})amine upon exposure to a stoichiometric amount of the metal salts cobalt(II) nitrate, vanadium(III) chloride, and iron(II) chloride. In the reaction with cobalt nitrate, the reduced ligand then chelates to the metal to form [N,N-bis(2-{pyrid-2-ylethyl})amine]dinitrocobalt(II). Upon reaction with vanadium(III) chloride and iron(III) chloride, the reduced ligand is isolated as the protonated free base, resulting from a metal-mediated decomposition reaction.

Radiotracer method to study the transport of mercury(II)chloride from water to sediment and air

International Nuclear Information System (INIS)

Karaca, F.; Aras, N.K.

2004-01-01

The fate of dissolved Hg(II) in surface waters is an important component of the Hg cycle. A simple experimental methodology was used to understand and measure the transport of Hg(II) from water to air and sediment. The use of radioactive dissolved Hg tracer for the determination of evasion and deposition is found to be a very useful technique. The evasion of mercury was investigated during a 140-hour period. It was observed that about a quarter of mercury chloride remained in the water phase, the other quarter was emitted via the evasion process and half of it deposited in sediment. (author)

Study of the removal of mercury(II) and chromium(VI) from aqueous solutions by Moroccan stevensite

International Nuclear Information System (INIS)

Benhammou, A.; Yaacoubi, A.; Nibou, L.; Tanouti, B.

2005-01-01

The objective of the present study was to investigate the adsorption of the heavy metals mercury(II) and chromium(VI), from aqueous solutions, onto Moroccan stevensite. A mineralogical and physicochemical characterization of natural stevensite was carried out. In order to improve the adsorption capacity of stevensite for Cr(VI), a preparation of stevensite was carried out. It consists in saturating the stevensite by ferrous iron Fe(II) and reducing the total Fe by Na 2 S 2 O 4 . Then, the adsorption experiments were studied in batch reactors at 25 ± 3 deg. C. The influence of the pH solution on the Cr(VI) and Hg(II) adsorption was studied in the pH range of 1.5-7.0. The optimum pH for the Cr(VI) adsorption is in the pH range of 2.0-5.0 while that of Hg(II) is at the pH values above 4.0. The adsorption kinetics were tested by a pseudo-second-order model. The adsorption rate of Hg(II) is 54.35 mmol kg -1 min -1 and that of Cr(VI) is 7.21 mmol kg -1 min -1 . The adsorption equilibrium time for Hg(II) and Cr(VI) was reached within 2 and 12 h, respectively. The adsorption isotherms were described by the Dubinin-Radushkevich model. The maximal adsorption capacity for Cr(VI) increases from 13.7 (raw stevensite) to 48.86 mmol kg -1 (modified stevensite) while that of Hg(II) decreases from 205.8 to 166.9 mmol kg -1 . The mechanism of Hg(II) and Cr(VI) adsorption was discussed

The electrochemistry of chromium, chromium-boron and chromium-phosphorus alloys

International Nuclear Information System (INIS)

Moffat, T.P.; Ruf, R.R.; Latanision, R.M.

1987-01-01

It is fairly well established that chromium-metalloid interactions represent the key to understanding the remarkable corrosion behavior of TM-Cr-M glasses; (Fe, Ni, Co,...)-Cr-(P, Si, C, S). The character and kinetics of passive film growth on the glasses are being studied ni order to assess the role of the film former, chromium, and the metalloids in the passivation process. A series of thin film microcrystalline chromium, Cr-B and Cr-P binary alloys have been fabricated by physical vapor deposition techniques. Vacuum melted conventionally processed chromium has also been studied. Examination of these materials in lM H/sub 2/SO/sub 4/ and lM HCl by voltammetry, potentiostatic and impedance techniques yields the following conclusion: 1. Pure chromium with a grain size varying from < 400 A to 0.5 mm exhibits no well defined differences in electrochemical behavior in lM H/sub 2/SO/sub 4/. 2. The tremendous corrosion resistance of Cr-B alloys has been confirmed. 3. The beneficial effects observed for boron alloyed with chromium may be considered surprising in view of the neutral/negative influence of alloying boron with iron, i.e. Fe/sub 80/B/sub 20/. 4. The interaction of the electrochemistry of the metalloid constituent with that of the transition base element determines the corrosion behavior. 5. Preliminary work with Cr-P alloys indicates that certain compositions exhibit promising properties - certain films were found to be intact after two days of immersion in concentrated HCl. Further work is in progress

Comparative assessment of gastrointestinal irritant potency in man of tin(II) chloride and tin migrated from packaging.

Science.gov (United States)

Boogaard, Peter J; Boisset, Michel; Blunden, Steve; Davies, Scot; Ong, Teng Jin; Taverne, Jean-Pierre

2003-12-01

Tin is present in low concentrations in most canned foods and beverages, the highest levels being found in products packaged in unlacquered or partially lacquered tinplate cans. A limited number of case-reports of acute gastrointestinal disorders after consumption of food containing 100-500 mg/kg tin have been reported, but these reports suffer many insufficiencies. Controlled clinical studies on acute effects of tin migrated from packaging suggest a threshold concentration for adverse effects (AEs) of >730 mg/kg. Two separate randomised, single-centre, double-blind, crossover studies, enabling comparison of the tolerability of tin added as tin(II) chloride at concentrations of soup in 24 volunteers (Study 2) were carried out. Distribution studies were conducted to get insight in the acute AEs of low molecular weight (clear dose-response relationship was only observed when tin was added as tin(II) chloride in tomato juice. No clinically significant AEs were reported in Study 2 and comparison of the incidence of tin-related AEs showed no difference between the dose levels (including control). Tin species of low molecular weight in supernatant represented 31-32% of total tin in canned tomato soup versus 56-61% in juice freshly spiked with tin(II) chloride. Differences in the incidence of AEs following administration of tomato juice with 161 and 264 mg of tin per kg and tomato soup with 201 and 267 mg of tin per kg likely results from differences in the concentration of low molecular weight tin species and in the nature of tin complexes formed. The results of this work demonstrate that tin levels up to 267 mg/kg in canned food cause no AEs in healthy adults and support the currently proposed tin levels of 200 mg/kg and 250 mg/kg for canned beverages and canned foods, respectively, as safe levels for adults in the general population.

Dietary inclusion of chromium to improve growth performance and immune-competence of broilers under heat stress

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Tagwa M. Norain

2013-11-01

Full Text Available This study was conducted to investigate the effects of dietary supplementation with chromium chloride, CrCl3.6H2O (2mg kg–1 basal diet on the performance and immune response of broiler chickens under heat stress condition (25-43°C. A total of 80 one-day-old broiler chicks (Ross-308 were assigned to two treatment groups according to a completely randomized design. Each treatment consisted of four equal replicates, each contained ten chicks. Chicks were fed on basal diets supplemented with different concentrations of chromium (0 and 2 mg kg–1 CrCl3 from 1 to 35 days of age. Chromium supplementation as feed additives resulted in a slightly lower rectal temperature, and significantly (P<0.05 lower respiration rate for the broiler chickens received diet supplemented with chromium compared to the control (0 mg kg–1 CrCl3. Dietary chromium supplementation increased final body weight (BW at the end of the production period (5 weeks. Average weight gain was significantly (P<0.05 higher in chickens fed on chromium supplemented diet. Feed intake was not influenced by dietary chromium supplementation, however, the efficiency of feed conversion was improved (P<0.05 in chromium supplemented chickens. Furthermore, dressing percentage was significantly (P<0.05 higher in Cr-treated chickens compared to control chickens. Chromium supplementation significantly (P<0.05 improved the immune response to Newcastle Disease Virus vaccine (NDV. The present results suggest that dietary chromium supplementation provides a good nutritional management approach to ameliorate heat stress induced depression in production performance and immune response of broiler chickens. 

Chloride is essential for contraction of afferent arterioles after agonists and potassium

DEFF Research Database (Denmark)

Jensen, B L; Ellekvist, Peter; Skøtt, O

1997-01-01

to norepinephrine, angiotensin II (ANG II), and potassium were measured after chloride depletion and compared with controls. Chloride depletion did not change arteriolar diameters, but the response to norepinephrine was markedly reduced when chloride was substituted with gluconate (n = 6) or isethionate (n = 6......). Reintroduction of chloride fully restored the sensitivity to norepinephrine. Contractions after ANG II and potassium were totally abolished in the absence of chloride (n = 6). In additional experiments (n = 7), the arteriolar contraction to 100 mM potassium was abolished only 1 min after removal of extracellular......A depolarizing chloride efflux has been suggested to activate voltage-dependent calcium channels in renal afferent arteriolar smooth muscle cells in response to vasoconstrictors. To test this proposal, rabbit afferent arterioles were microperfused, and the contractile dose responses...

Progress in the chemistry of chromium(V) doping agents used in polarized target materials

International Nuclear Information System (INIS)

Krumpolc, M.; Hill, D.; Struhrmann, H.B.

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

Role of paramagnetic chromium in chromium(VI)-induced damage in cultured mammalian cells.

OpenAIRE

Sugiyama, M

1994-01-01

Chromium(VI) compounds are known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to chromium(III), the formation of paramagnetic chromium such as chromium(V) and chromium(III) is believed to play a role in the adverse biological effects of chromium(VI) compounds. The present report, uses electron spin resonance (ESR) spectroscopy; the importance of the role of paramagnetic chromium in chromium(VI)-induced damage in intac...

Biochemical and Hematological Profiles of Common Carp (Cyprinus Carpio under Sublethal Effects of Trivalent Chromium

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Zeynab Abedi

2016-07-01

Full Text Available Background: In natural waters and/or aquaculture facilities, fish are often exposed to chromium waste and demonstrate cumulative deleterious effects. To our knowledge, there are no studies concerning the effects of trivalent Cr on C. carpio hematology. This study presents hematological and some biochemical parameters of common carp, Cyprinus carpio, affected by sublethal concentration of trivalent chromium. Methods: The fish in the experimental aquaria (three replicates each were exposed to a sublethal chromium chloride concentration of 2 mg L−1, which was prepared as stock solution and added depending on the volume of the aquaria to obtain the required concentration. After a period of 28 days, parameters such as hematocrit (Hct, hemoglobin (Hb, lymphocytes (Lym, neutrophils (Neu, total protein (TP, albumin, immunoglobulin M (IgM, glucose, red and white blood cells (RBC and WBC, mean corpuscular volume (MCV, mean corpuscular hemoglobin (MCH, and mean corpuscular hemoglobin concentration (MCHC were examined. Results: Chromium exposure for 28 days significantly (P0.05 between the Cr-exposed fish and the control. Conclusion: Hematological indices of fish, caused by chromium toxicity to C. carpio, can be secondary responses to toxicants, including exposure to low concentrations of heavy metals, which reflect the launch of stress reaction in the affected fish.

Selective and Efficient Solvent Extraction of Copper(II Ions from Chloride Solutions by Oxime Extractants

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Zahra Kaboli Tanha

2016-06-01

Full Text Available Oxime extractants 3-tert-butyl-2-hydroxy-5-methyl benzaldehyde oxime (HL1 and 3-tert-butyl-2-hydroxy-5-methoxy benzaldehyde oxime (HL2 were synthesized and characterized by conventional spectroscopic methods. Suitable lipophilic nature of the prepared extractants allowed examining the ability of these molecules for extraction-separation of copper from its mixture with normally associated metal ions by performing competitive extraction experiments of Cu(II, Co(II, Ni(II, Zn(II, Cd(II and Pb(II ions from chloride solutions. Both ligands transfer selectively the copper ions into dichloromethane by a cation exchange mechanism. Conventional log-log analysis and isotherm curves showed that Cu(II ions are extracted as the complexes with 1:2 metal to ligand ratio by both extractants. Verification of the effect of the organic diluent used in the extraction of copper ions by HL1 and HL2 demonstrated that the extraction efficiency varies as: dichloromethane ~ dichloroethane > toluene > xylene > ethylacetate. Time dependency investigation of the extraction processes revealed that the kinetics of the extraction of copper by HL2 is more rapid than that of HL1. The application of the ligands for extraction-separation of copper ions from leach solutions of cobalt and nickel-cadmium filter-cakes of a zinc production plants was evaluated.

Chromium allergy

DEFF Research Database (Denmark)

Hansen, M B; Johansen, J D; Menné, Torkil

2003-01-01

Most studies investigating chromium allergy have been performed with Cr(VI). However, real exposure to chromium from leather products includes both Cr(III) and Cr(VI). We have determined and compared the minimum elicitation threshold (MET) concentration for Cr(III) and Cr(VI) in Cr(VI)-sensitive ......Most studies investigating chromium allergy have been performed with Cr(VI). However, real exposure to chromium from leather products includes both Cr(III) and Cr(VI). We have determined and compared the minimum elicitation threshold (MET) concentration for Cr(III) and Cr(VI) in Cr......(III) was concluded to play an important role in chromium allergy, because Cr(III) and Cr(VI) were both capable of eliciting eczema at low concentrations. Rather than regarding chromium dermatitis as a result of Cr(VI) allergy alone, it may be more correct to consider it as a result of a combined Cr(III) and Cr......(VI) allergy....

Toxic effect evaluation of the lead acetate and chromium chloride on anaerobic bacterial metabolism

International Nuclear Information System (INIS)

Wills, Beatriz; Naranjo, Fernando

2004-01-01

The toxicity of trivalent chromium and lead to anaerobic sludge system was studied. Performed assay was tested in 60 mL serum vials, the toxicity test to succeed in two steps, first with formic acid and then whey powder as a substrate. Anaerobic toxicity assays were performed taking into account, methane gas production and oxidation-reduction potential (ORP) rate, these tests were considered a useful indicator for monitoring a anaerobic sludge suffering from toxicants, over 72 hours with metals dosage against the control. First of all, exploratory assays in order to know different chromium and lead concentrations were carried out. The assays degradation activity reduced methane by 50% that came into contact with 3.322 mg Cr 3 +/L and 1.415 mg Pb/L and 2.291 mg Cr 3 +/Land 1.982 mg Pb/L with formic acid and whey powder as a substrate respectively. Heavy metal concentrations that caused 50% inhibition of methanogenesis during whey and formic acid methanation indicated that toxicity decreased in order Pb>>Cr

Microwave Mapping Demonstration Using the Thermochromic Cobalt Chloride Equilibrium

Science.gov (United States)

Nguyen, Vu D.; Birdwhistell, Kurt R.

2014-01-01

An update to the thermochromic cobalt(II) chloride equilibrium demonstration is described. Filter paper that has been saturated with aqueous cobalt(II) chloride is heated for seconds in a microwave oven, producing a color change. The resulting pink and blue map is used to colorfully demonstrate Le Châtelier's principle and to illuminate the…

Two-electron oxidation of cobalt phthalocyanines by thionyl chloride: Implications for lithium/thionyl chloride batteries. Technical report

Energy Technology Data Exchange (ETDEWEB)

Bernstein, P.A.; Lever, A.B.

1989-10-20

Cyclic voltammetry, DPV and electronic spectroscopy are used to study the reaction between thionyl chloride and cobalt phthalocyanine. SOCl2 reacts with (Co(I)Tn Pc(2-)) and Co(II)Tn Pc(2-) to give two-electron oxidized species. Implications for Li/SOCl2 batteries are discussed. Thionyl chloride also forms a mono SOCl2 adduct with Co(II)TnPc(2-). Driving forces (Delta E values) were calculated for CoTnPc comproportionation and CoTnPc + SOCl2 reactions. Rest potential measurements of a Li/SOCl2 cells show that addition of AlCl3 stabilizes the LiCl product as LiAlCl4. A catalytic two-electron mechanism is indicated for the reduction of thionyl chloride in a Li/SOCl2/(CoTnPc,C) battery.

Contribution to the study of the biological properties of compounds labeled with radio-chromium 51Cr

International Nuclear Information System (INIS)

Ingrand, J.

1964-07-01

Among the radioisotopes commonly used in biology and medicine which are controlled Individually in the Radioelement Departement of the Saclay Nuclear Research Centre before being sent to the users, the author has chosen chromium 51 incorporated in inorganic salts or in organic substrates for a study of the biological properties of the compounds. In the first part, he has compared the pathways followed by the radioactive sodium chromate and chromic chloride mixed with blood or given to the whole animal, the object being to determine whether a reduction of hexavalent chromium occurs, both in vitro and in vivo. In the second part, the author has tried to show the validity of using, various substrates labeled with chromium 51, red cells, haemoglobin, plasma proteins and cytochrome c. The results obtained have contributed to underline the interest of using such compounds for biological applications. (author) [fr

Chromium

Science.gov (United States)

... 2 Whole wheat bread, 2 slices 2 Red wine, 5 ounces 1–13 Apple, unpeeled, 1 medium ... chromium or a placebo) might simply show the benefits of supplementation in a chromium-deficient population. Overall, ...

Hydrolysis of cupric chloride in aqueous ammoniacal ammonium chloride solutions

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Limpo, J. L.

1995-06-01

Full Text Available Cupric solubility in the CuCl₂-NH₄Cl-NH₃-H₂O system for chloride concentrations lower than 4 molal in the temperature range 25-60 °C was studied. The experimental results show that for chloride concentration between 3.0 and 1.0 molal the cupric solubility is determined by the solubility of the cupric hydroxychloride Cu(OH_1.5Cl_0.5. For a chloride concentration value of 4.0 molal, there are two cupric compounds, the hydroxychloride Cu(OH_1.5Cl_0.5 or the diammine chloride Cu(NH₃₂Cl₂, on which the solubility of Cu(II depends, according to the temperature and the value of the ratio [NH₃]_Total/[Cu]_Total.

Se estudia la solubilidad del Cu(II en el sistema CuCl₂-NH₄Cl-NH₃-H₂O para concentraciones de cloruro inferiores a 4 molal en el intervalo de temperaturas 25-60 °C. Los resultados experimentales muestran que, para concentraciones de cloruros comprendidas entre 3,0 y 1,0 molal, la solubilidad cúprica viene determinada por la solubilidad del hidroxicloruro cúprico, Cu(OH_1.5Cl_0.5. Para concentraciones de cloruro 4,0 molal, existen dos compuestos cúpricos, el hidroxicloruro, Cu(OH_1.5Cl_0.5 o el cloruro de diamina, Cu(NH₃₂Cl₂, de los que, de acuerdo con la temperatura y con el valor de la relación [NH₃]_Total/[Cu]_Total depende la solubilidad del Cu(II.

The role of chloride in the mechanism of O(2) activation at the mononuclear nonheme Fe(II) center of the halogenase HctB.

Science.gov (United States)

Pratter, Sarah M; Light, Kenneth M; Solomon, Edward I; Straganz, Grit D

2014-07-02

Mononuclear nonheme Fe(II) (MNH) and α-ketoglutarate (α-KG) dependent halogenases activate O2 to perform oxidative halogenations of activated and nonactivated carbon centers. While the mechanism of halide incorporation into a substrate has been investigated, the mechanism by which halogenases prevent oxidations in the absence of chloride is still obscure. Here, we characterize the impact of chloride on the metal center coordination and reactivity of the fatty acyl-halogenase HctB. Stopped-flow kinetic studies show that the oxidative transformation of the Fe(II)-α-KG-enzyme complex is >200-fold accelerated by saturating concentrations of chloride in both the absence and presence of a covalently bound substrate. By contrast, the presence of substrate, which generally brings about O2 activation at enzymatic MNH centers, only has an ∼10-fold effect in the absence of chloride. Circular dichroism (CD) and magnetic CD (MCD) studies demonstrate that chloride binding triggers changes in the metal center ligation: chloride binding induces the proper binding of the substrate as shown by variable-temperature, variable-field (VTVH) MCD studies of non-α-KG-containing forms and the conversion from six-coordinate (6C) to 5C/6C mixtures when α-KG is bound. In the presence of substrate, a site with square pyramidal five-coordinate (5C) geometry is observed, which is required for O2 activation at enzymatic MNH centers. In the absence of substrate an unusual trigonal bipyramidal site is formed, which accounts for the observed slow, uncoupled reactivity. Molecular dynamics simulations suggest that the binding of chloride to the metal center of HctB leads to a conformational change in the enzyme that makes the active site more accessible to the substrate and thus facilitates the formation of the catalytically competent enzyme-substrate complex. Results are discussed in relation to other MNH dependent halogenases.

Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

International Nuclear Information System (INIS)

Anon.

1981-01-01

This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0% and nickel does not exceed 50.0%

Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

International Nuclear Information System (INIS)

Anon.

1981-01-01

This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes are normally used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

From polyethylene waxes to HDPE using an α,α'-bis(arylimino)-2,3:5,6-bis(pentamethylene)pyridyl-chromium(iii) chloride pre-catalyst in ethylene polymerisation.

Science.gov (United States)

Huang, Chuanbing; Du, Shizhen; Solan, Gregory A; Sun, Yang; Sun, Wen-Hua

2017-05-30

Five examples of α,α'-bis(arylimino)-2,3:5,6-bis(pentamethylene)pyridyl-chromium(iii) chlorides (aryl = 2,6-Me 2 Ph Cr1, 2,6-Et 2 Ph Cr2, 2,6-i-Pr 2 Ph Cr3, 2,4,6-Me 3 Ph Cr4, 2,6-Et 2 -4-MePh Cr5) have been synthesized by the one-pot template reaction of α,α'-dioxo-2,3:5,6-bis(pentamethylene)pyridine, CrCl 3 ·6H 2 O and the corresponding aniline. The molecular structures of Cr1 and Cr4 reveal distorted octahedral geometries with the N,N,N-ligand adopting a mer-configuration. On activation with an aluminium alkyl co-catalyst, Cr1-Cr5 exhibited high catalytic activities in ethylene polymerization and showed outstanding thermal stability operating effectively at 80 °C with activities up to 1.49 × 10 7 g of PE (mol of Cr) -1 h -1 . Significantly, the nature of the co-catalyst employed had a dramatic effect on the molecular weight of the polymeric material obtained. For example, using diethylaluminium chloride (Et 2 AlCl) in combination with Cr4 gave high density/high molecular weight polyethylene with broad molecular weight distributions (30.9-39.3). By contrast, using modified methylaluminoxane (MMAO), strictly linear polyethylene waxes of lower molecular weight and narrow molecular weight distribution (1.6-2.0) were obtained with vinyl end-groups.

Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

International Nuclear Information System (INIS)

Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

1978-01-01

Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)

Laboratory Validation and Demonstrations of Non-Hexavalent Chromium Conversion Coatings for Steel Substrates (Briefing Charts)

Science.gov (United States)

2011-02-01

UNCLASSIFIED: Approved for public release; distribution unlimited. Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion...00-00-2011 4. TITLE AND SUBTITLE Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion Coatings for Steel Substrates 5a...to MRAP II Acquisition Pretreatment /conversion coatings omitted: • Hex- chrome pretreatments prohibited for new ground vehicles • Hydrogen

Specification for corrosion-resisting chromium and chromium-nickel steel covered welding electrodes

International Nuclear Information System (INIS)

Anon.

1983-01-01

This specification prescribes requirements for covered corrosion-resisting chromium and chromium-nickel steel electrodes. These electrodes normally are used for shielded metal arc welding, and include those alloy steels designated as corrosion or heat-resisting chromium-nickel steels in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

Colloid formation as an approach to remediate toxic wastes containing chromium and lead

Energy Technology Data Exchange (ETDEWEB)

Barton, Larry L [Laboratory of Microbial Chemistry, Department of Biology, University of New Mexico, Albuquerque, NM (United States); Lindemann, William C [Department of Agronomy and Horticulture, New Mexico State University, Las Cruces, NM (United States); Bearden, Deborah L [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM (United States)

1992-07-01

We have explored the use of bacteria to remediate soil and aquatic sites containing toxic levels of Pb II or Cr VI. Bacterial isolates from metal-containing sites are capable of detoxifying water containing up to 10 mM Pb II. This activity is a two step process with an initial binding of Pb II to the cells followed by production of a black Pb-containing colloid. Numerous bacteria will reduce Cr VI to Cr III and some isolates have been found to bind Cr III to the bacterial cell. Colloids consisting of Cr III would result from the formation of chromium hydroxide or from binding to bacteria. The bacterial metabolism of Pb II and Cr III converts the biologically toxic and chemically reactive metal to compounds of reduced toxicity and modified chemical activity. We propose a system which can employ bacteria for the bioremediation of toxic sites containing lead or chromium. (author)

Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

DEFF Research Database (Denmark)

Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B

2012-01-01

Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

Chromium removal from tanning industries effluents

International Nuclear Information System (INIS)

Chaudry, M.A.; Ahmad, S.

1997-01-01

Air and water are the basic needs of human being and other living entities on the earth. Tanning industry uses water and some chemicals and so creates environmental problems, depending basically on two principal sources, hide and water. The processes of tanning are based on chromium sulphate and vegetable treatment of hide. According to the national environmental quality standards (NEQS) the effluent or disposed water should contain phenol less than 0.5 ppm, Cr, sulphates, chloride and other salts content. About 30-40 liters of water are used to process one Kg of raw hide into finished goods. Total installed capacity of hides and skins chrome tanning is 53.5 million square meter, earning a large amount of foreign exchange for our country. In the present work, seven tanning industries effluents from the suburbs of Multan city have been collected and analysed. The pH of the liquors have been found to vary from 2.72 to 4.4 and the constituent Cr have been found to be from zero to 8000 ppm from vegetable to chrome tanning industrial effluents studied. The stages involved in tanning and treatment of the effluent water waste including chemical treatment of Cr has been described with a special reference to supported liquid membranes process for removal of chromium ions. (author)

Stimulus responsive hydrogel-coated etched fiber Bragg grating for carcinogenic chromium (VI) sensing

Science.gov (United States)

Kishore, Pabbisetti Vayu Nandana; Madhuvarasu, Sai Shankar; Moru, Satyanarayana

2018-01-01

This paper proposes a chemo-mechanical-optical sensing approach for the detection of carcinogenic chromium (VI) metal ion using an etched fiber Bragg grating (FBG) coated with stimulus responsive hydrogel. Hydrogel synthesized from the blends of (3-acrylamidopropyl)-trimethylammonium chloride, which is highly responsive to chromium ions suffers a volume change when placed in Cr solution. When the proposed sensor system is exposed to various concentrations of Cr (VI) ion solution, FBG peak shifts due to the mechanical strain induced by the swelling of the hydrogel. The peak shift is correlated with the concentration of the Cr (VI) metal ion. Due to the reduction in the cladding diameter of FBG, wastage of swelling force due to hydrogel on FBG is lowered and utilized for more wavelength peak shift of FBG resulting in the increase in the sensitivity. The resolution of the sensor system is found to be 0.072 ppb. Trace amounts of chromium (VI) ion as low as 10 ppb can be sensed by this method. The sensor has shown good sensitivity, selectivity, and repeatability. The salient features of the sensors are its compact size, light weight, and adoptability for remote monitoring.

Heterogeneous chromium catalysts

NARCIS (Netherlands)

2005-01-01

The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based

Effect of nickel and chromium exposure on buccal cells of electroplaters.

Science.gov (United States)

Qayyum, Saba; Ara, Anjum; Usmani, Jawed Ahmad

2012-02-01

The electroplating industry commonly involves the use of nickel and chromium. An assessment of the genotoxic effects of these metals can be carried out by micronucleus (MN) test in buccal cells. Other nuclear anomalies (NA) observed in buccal cells viz., karyorrhexis, pyknosis and karyolysis are also the indicators of genotoxicity. The current study aims at determining the extent of genotoxic damage in relation to the duration of exposure to nickel and hexavalent chromium via micronuclei induction and other nuclear anomalies. The present investigation included 150 subjects of which 50 individuals with no history of nickel/chromium exposure (Group I) were taken as control, 50 electroplaters exposed to nickel and hexavalent chromium for duration of less than 10 years (Group II) and 50 electroplaters exposed for ≥10 years (Group III) were included. Slides of buccal cells were prepared and the frequency of MN (‰) and NA (‰) were calculated. ANOVA was applied to test significance. Results were considered significant at p exposure increased. Plasma nickel and chromium levels were also determined which showed a positive correlation with frequency MN and other nuclear abnormalities (p < 0.01).

Determination of chromium combined with DNA, RNA and protein in chromium-rich brewer's yeast

International Nuclear Information System (INIS)

Ding Wenjun; Qian Qinfang; Hou Xiaolin; Feng Weiyue; Chai Zhifang

2000-01-01

The contents of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast were determined with the neutron activation analysis in order to study the combination of Cr with DNA, RNA and protein in chromium-rich brewer's yeast. The results showed that the extracting rats and concentrations of DNA, RNA and protein had no significant difference in two types of yeast, but the chromium contents of DNA, RNA and protein in the chromium-rich yeast were significantly higher than those in the normal. In addition, the content of chromium in DNA was much higher than that in RNA and protein, which indicated that the inorganic chromium compounds entered into the yeast cell, during the yeast cultivation in the culture medium containing chromium were converted into organic chromium compounds combined with DNA, RNA and protein

Sorption of chromium(III) and chromium(VI) on lead sulfide

International Nuclear Information System (INIS)

Music, S.

1985-01-01

The sorption of chromium(III) and chromium(VI) on lead sulfide was investigated in dependence on pH, time of sorption, and on the concnetrations of sorbate and sorbent. The mechanisms of the sorption of Crsup(3+) and CrOsub(4)sup(2-) traces on lead sulfide are discussed; a difference between CrOsub(4)sup(2-) sorption on PbS and α-Fesub(2)Osub(3) was found. Sulfates and molybdates affect the removal of chromates from aqueous solutions. Lead sulfide carrier prepared in this work was also used for the preconcentration of chromium(III) and chromium(VI) from tap water. (author)

Electrodeposition behavior of nickel and nickel-zinc alloys from the zinc chloride-1-ethyl-3-methylimidazolium chloride low temperature molten salt

International Nuclear Information System (INIS)

Gou Shiping; Sun, I.-W.

2008-01-01

The electrodeposition of nickel and nickel-zinc alloys was investigated at polycrystalline tungsten electrode in the zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt. Although nickel(II) chloride dissolved easily into the pure chloride-rich 1-ethyl-3-methylimidazolium chloride ionic melt, metallic nickel could not be obtained by electrochemical reduction of this solution. The addition of zinc chloride to this solution shifted the reduction of nickel(II) to more positive potential making the electrodeposition of nickel possible. The electrodeposition of nickel, however, requires an overpotential driven nucleation process. Dense and compact nickel deposits with good adherence could be prepared by controlling the deposition potential. X-ray powder diffraction measurements indicated the presence of crystalline nickel deposits. Non-anomalous electrodeposition of nickel-zinc alloys was achieved through the underpotential deposition of zinc on the deposited nickel at a potential more negative than that of the deposition of nickel. X-ray powder diffraction and energy-dispersive spectrometry measurements of the electrodeposits indicated that the composition and the phase types of the nickel-zinc alloys are dependent on the deposition potential. For the Ni-Zn alloy deposits prepared by underpotential deposition of Zn on Ni, the Zn content in the Ni-Zn was always less than 50 atom%

Investigation of the surface composition of electrodeposited black chromium by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Survilienė, S.; Češūnienė, A.; Jasulaitienė, V.; Jurevičiūtė, I.

2015-01-01

Highlights: • Black chromium electrodeposited from a Cr(III) bath is composed of oxide, hydroxide and metallic chromium. • Metallic phase is absent in black chromium electrodeposited from a Cr(III) + ZnO bath. • The near-surface layer is rich in hydroxides, whereas oxides of both metals predominate in the depth of the coatings. - Abstract: The paper reviews black chromium electrodeposited from a trivalent chromium bath containing ZnO as a second main component. The chemical compositions of the top layers of the black chromium coatings were studied by the X-ray photoelectron spectroscopy method. The surface of black chromium was found to be almost entirely covered with organic substances. To gain information on the state of each element in the deposit bulk, the layer-by-layer etching of the black chromium surface with argon gas was used. Analysis of XPS spectra has shown that the top layers of black chromium without zinc are composed of various Cr(III) components, organic substances and metallic Cr, whereas metallic Cr is almost absent in black chromium containing some amount of Zn(II) compounds. The ratios of metal/oxide phases were found to be 10/27 and 2/28 for black chromium without and with zinc, respectively. It has been determined that owing to the presence of ZnO in the Cr(III) bath, the percentage of metallic chromium is substantially reduced in black chromium which is quite important for good solar selective characteristics of the coating. The results confirm some of earlier observations and provide new information on the composition of the near-surface layers

In vitro evaluation of bioremediation capacity of a commercial probiotic, Bacillus coagulans, for chromium (VI) and lead (II) toxicity.

Science.gov (United States)

Belapurkar, Pranoti; Goyal, Pragya; Kar, Anand

2016-01-01

The bioaccumulation of heavy metals including chromium (VI) (Cr (VI)) and lead (II) (Pb (II)) causes fatal toxicity in humans. Some naturally occurring bacterial genera such as Bacillus and Pseudomonas help in bioremediation of these heavy metals and some of the species of Bacillus are proven probiotics. However, no study has been conducted on Bacillus coagulans , which is a proven probiotic species of genus Bacillus . The primary objective of the present study was to assess the potential of a proven probiotic, B. coagulans , marketed as "Sporlac-DS," to survive in the presence of Cr (VI) and Pb (II) and its ability to reduce its concentration in vitro . The Minimum inhibitory concentration (MIC) of the organism for Cr (VI) and Pb (II) was determined followed by its biochemical and morphological characterization. Its antibiotic sensitivity and probiotic efficacy were assessed. Further, its bioremediation capacity was observed in vitro by determining the residual Cr (VI) and Pb (II) concentration after 72 h. B. coagulans could tolerate up to 512 ppm concentration of Cr (VI) and had an MIC of 128 ppm for Pb (II). After 72 h, the organism reduced 32 ppm Cr (VI) and 64 ppm Pb (II) by 93% and 89%, respectively. When B. coagulans was studied before and after growing on Cr (VI) and Pb (II) for 24 h, an increase was seen in sensitivity toward the tested antibiotics whereas no change was observed in morphological and biochemical characters. It also showed no change in their bile and acid tolerance, indicating that it retains its probiotic efficacy. The tested probiotic B. coagulans may have a potential role in bioremediation of Cr (VI) and Pb (II), in vivo .

Effects of surface chromium depletion on localized corrosion of alloy 825 as a high-level nuclear waste container material

International Nuclear Information System (INIS)

Dunn, D.S.; Sridhar, N.; Cragnolino, G.A.

1995-01-01

Effects of the chromium-depleted, mill-finished surface on the localized corrosion resistance of alloy 825 (UNS N08825) were investigated. Tests were conducted in solutions based on the ground water at Yucca mountain, Nevada, but with a higher concentration of chloride. Results indicated that breakdown (E p ) and repassivation (E rp ) potentials for mill-finished surfaces were more active than those for polished surfaces. Potentiodynamic polarization tests indicated pits could be initiated on the chromium-depleted surface at potentials of 220 mV SCE in a solution containing 1,000 ppm Cl - at 95 C. Potentiostatic tests identified a similar pit initiation potential for the mill-finished surface. However, under longterm potentiostatic tests, a higher potential of 300 mV SCE was needed to sustain stable pit growth beyond the chromium-depleted layer. An increase in surface roughness also was observed to decrease localized corrosion resistance of the material

Removal of hexavalent chromium from wastewater using a new composite chitosan biosorbent.

Science.gov (United States)

Boddu, Veera M; Abburi, Krishnaiah; Talbott, Jonathan L; Smith, Edgar D

2003-10-01

A new composite chitosan biosorbent was prepared by coating chitosan, a glucosamine biopolymer, onto ceramic alumina. The composite bioadsorbent was characterized by high-temperature pyrolysis, porosimetry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Batch isothermal equilibrium and continuous column adsorption experiments were conducted at 25 degrees C to evaluate the biosorbent for the removal of hexavalent chromium from synthetic as well as field samples obtained from chrome plating facilities. The effect of pH, sulfate, and chloride ion on adsorption was also investigated. The biosorbent loaded with Cr(VI) was regenerated using 0.1 M sodium hydroxide solution. A comparison of the results of the present investigation with those reported in the literature showed that chitosan coated on alumina exhibits greater adsorption capacity for chromium(VI). Further, experimental equilibrium data were fitted to Langmuir and Freundlich adsorption isotherms, and values of the parameters of the isotherms are reported. The ultimate capacity obtained from the Langmuir model is 153.85 mg/g chitosan.

Development of low-chromium, chromium-tungsten steels for fusion

International Nuclear Information System (INIS)

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

1995-01-01

High-chromium (9-12% Cr) Cr-Mo and Cr-W ferritic steels are favored as candidates for fusion applications. In early work to develop reduced-activation steels, an Fe-2.25Cr-2W-0.25V-0.1C steel (designated 2.25Cr-2WV) had better strength than an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) steel (compositions are in weight percent). However, the 2.25Cr-2WV had poor impact properties, as determined by the ductile-brittle transition temperature and upper-shelf energy of subsize Charpy impact specimens. Because low-chromium steels have some advantages over high-chromium steels, a program to develop low-chromium steels is in progress. Microstructural analysis indicated that the reason for the inferior impact toughness of the 2.25Cr-2WV was the granular bainite obtained when the steel was normalized. Properties can be improved by developing an acicular bainite microstructure by increasing the cooling rate after austenitization. Alternatively, acicular bainite can be promoted by increasing the hardenability. Hardenability was changed by adding small amounts of boron and additional chromium to the 2.25Cr-2WV composition. A combination of B, Cr, and Ta additions resulted in low-chromium reduced-activation steels with mechanical properties comparable to those of 9Cr-2WVTa. (orig.)

Determination of chromium(III) and total chromium in marine waters

Energy Technology Data Exchange (ETDEWEB)

Gardner, M J [WRc, Henley Road, Medmenham, Marlow SL7 2HD (United Kingdom); Ravenscroft, J E [WRc, Henley Road, Medmenham, Marlow SL7 2HD (United Kingdom)

1996-03-01

The development of an analytical technique is described which may be used to determine chromium, chromium(III) and chromium(VI) in estuarine and coastal waters. The method is based on selective micro-solvent extraction with subsequent GFAAS. The technique has been applied in a major North Sea estuary. The results obtained confirm that thermodynamic factors alone cannot be relied upon to describe the form of chromium in estuaries. Kinetic factors appear to have a strong influence over speciation and lead to the persistence of Cr(III) species in environments where Cr(VI) would be expected to be present. (orig.). With 5 figs., 2 tabs.

Effects of chloride, sulfate and natural organic matter (NOM) on the accumulation and release of trace-level inorganic contaminants from corroding iron.

Science.gov (United States)

Peng, Ching-Yu; Ferguson, John F; Korshin, Gregory V

2013-09-15

This study examined effects of varying levels of anions (chloride and sulfate) and natural organic matter (NOM) on iron release from and accumulation of inorganic contaminants in corrosion scales formed on iron coupons exposed to drinking water. Changes of concentrations of sulfate and chloride were observed to affect iron release and, in lesser extent, the retention of representative inorganic contaminants (vanadium, chromium, nickel, copper, zinc, arsenic, cadmium, lead and uranium); but, effects of NOM were more pronounced. DOC concentration of 1 mg/L caused iron release to increase, with average soluble and total iron concentrations being four and two times, respectively, higher than those in the absence of NOM. In the presence of NOM, the retention of inorganic contaminants by corrosion scales was reduced. This was especially prominent for lead, vanadium, chromium and copper whose retention by the scales decreased from >80% in the absence of NOM to chloride levels. Modeling indicated that the observed effects were associated with the formation of metal-NOM complexes and effects of NOM on the sorption of the inorganic contaminants on solid phases that are typical for iron corrosion in drinking water. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Incorporation of Chromium in Rice Straw Fermented with Ganoderma lucidum

Directory of Open Access Journals (Sweden)

F. Agustin

2013-04-01

Full Text Available The research was designed to evaluate chromium incorporation by Ganoderma lucidum in rice straw substrate supplemented with chromium chloride. Treatments were combination of Cr level (0, 500, 1000, 1500, 2000, 25000, and 3000 ppm and fermentation time (0, 2, 3, and 4 wk. The treatments were arranged in a factorial 7 x 4 and allocated in completely randomized design with three replications. G. lucidum was grown in potato dextrose agar (PDA medium for 10 days and was inoculated to the substrate which have been sterilized and mixed with CrCl3.6H2O. The moisture of substrate was maintained at 70%. Fiber and protein components of growth media of G. lucidum was determined and analyzed for their Cr content. The finding result showed that addition of Cr up to 3000 ppm into the substrate stimulated the G. lucidum growth. Chromium was incorporated into the fiber and protein components of the growth substrate of G. lucidum during fermentation. Incorporation of Cr into the protein of substrate containing 3000 ppm Cr was highest when fermented for 4 wk. Protein component of substrate contained 9.29% Cr while in NDF and ADF was 27.20% and 10.55% Cr, respectively. It is concluded that Cr was incorporated into the G. lucidum cells during fermentation.

EPR of Cu(II) in sarcosine cadmium chloride: probe into dopant site - symmetry and copper-sarcosine interaction

CERN Document Server

Pathinettam-Padiyan, D; Murugesan, R

2000-01-01

The electron paramagnetic resonance spectra of Cu(II) doped sarcosine cadmium chloride single crystals have been investigated at room temperature. Experimental results reveal that the Cu(II) ion enters the lattice interstitially. The observed superhyperfine lines indicate the superposition of two sets of quintet structure with interaction of nitrogen atoms and the two isotopes of copper. The spin Hamiltonian parameters are evaluated by Schonland method and the electric field symmetry around the copper ion is rhombic. An admixture of d sub z sup 2 orbital with the d sub x sub sup 2 sub - sub y sub sup 2 ground state is observed. Evaluation of MO coefficients reveals that the in-plane interaction between copper and nitrogen is strong in this lattice.

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

International Nuclear Information System (INIS)

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

1995-01-01

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

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

International Nuclear Information System (INIS)

Smith, W.H.; Purdy, G.

1995-01-01

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

In vitro evaluation of bioremediation capacity of a commercial probiotic, Bacillus coagulans, for chromium (VI and lead (II toxicity

Directory of Open Access Journals (Sweden)

Pranoti Belapurkar

2016-01-01

Full Text Available Introduction: The bioaccumulation of heavy metals including chromium (VI (Cr (VI and lead (II (Pb (II causes fatal toxicity in humans. Some naturally occurring bacterial genera such as Bacillus and Pseudomonas help in bioremediation of these heavy metals and some of the species of Bacillus are proven probiotics. However, no study has been conducted on Bacillus coagulans, which is a proven probiotic species of genus Bacillus. Objectives: The primary objective of the present study was to assess the potential of a proven probiotic, B. coagulans, marketed as “Sporlac-DS,” to survive in the presence of Cr (VI and Pb (II and its ability to reduce its concentration in vitro. Materials and Methods: The Minimum inhibitory concentration (MIC of the organism for Cr (VI and Pb (II was determined followed by its biochemical and morphological characterization. Its antibiotic sensitivity and probiotic efficacy were assessed. Further, its bioremediation capacity was observed in vitro by determining the residual Cr (VI and Pb (II concentration after 72 h. Results: B. coagulans could tolerate up to 512 ppm concentration of Cr (VI and had an MIC of 128 ppm for Pb (II. After 72 h, the organism reduced 32 ppm Cr (VI and 64 ppm Pb (II by 93% and 89%, respectively. When B. coagulans was studied before and after growing on Cr (VI and Pb (II for 24 h, an increase was seen in sensitivity toward the tested antibiotics whereas no change was observed in morphological and biochemical characters. It also showed no change in their bile and acid tolerance, indicating that it retains its probiotic efficacy. Conclusion: The tested probiotic B. coagulans may have a potential role in bioremediation of Cr (VI and Pb (II, in vivo.

Kinetics study of Jatropha oil esterification with ethanol in the presence of tin (II) chloride catalyst for biodiesel production

Science.gov (United States)

Kusumaningtyas, Ratna Dewi; Ratrianti, Naomi; Purnamasari, Indah; Budiman, Arief

2017-01-01

Jatropha oil is one of the promising feedstocks for biodiesel production. Jatropha oil is non-edible oil hence utilization of this oil would not compete with the needs of food. However, crude jatropha oil usually has high free fatty acid (FFA) content. Due to this fact, direct alkaline-catalyzed transesterification of crude jatropha oil for biodiesel production cannot be performed. FFA in crude jatropha oil will react with a base catalyst, resulting in soap as by product and hindering methyl ester (biodiesel) production. Therefore, prior to a transesterification reaction, it is crucial to run a pretreatment step of jatropha oil which can lower the FFA content in the oil. In this work, the pretreatment process was conducted through the esterification reaction of FFA contained in crude jatropha oil with ethanol over tin (II) chloride catalyst to reduce the acid value of the feedstock. The feedstock was Indonesia crude jatropha oil containing 12.03% of FFA. The esterification reaction was carried out in a batch reactor with a molar ratio of FFA to ethanol was 1:60 and total reaction time was 180 minutes. Tin (II) chloride catalyst was varied at 2.5, 5, 7.5, and 10% wt, whereas the effect of the reaction temperature was studied at 35, 34, 55, and 65 °C. The best reaction conversion was 71.55%, achieved at the following condition: a reaction temperature of 65 °C, catalyst concentration of 10% wt, the reaction time of 180 min, and the molar ratio of FFA to ethanol was 1:60. Kinetics study was also conducted in this work. It was found that esterification reaction of jatropha oil FFA with ethanol catalyzed by tin(II) chloride fitted the first-order pseudo-homogeneous kinetics model. It was also revealed that the frequency factor (A) and the activation energy (Ea) were 4.3864 × 106 min-1 and 56.2513 kJ/mole, respectively.

Hexavalent Chromium Minimization Strategy

Science.gov (United States)

2011-05-01

Logistics 4 Initiative - DoD Hexavalent Chromium Minimization Non- Chrome Primer IIEXAVAJ ENT CHRO:M I~UMI CHROMIUM (VII Oil CrfVli.J CANCEfl HAnRD CD...Management Office of the Secretary of Defense Hexavalent Chromium Minimization Strategy Report Documentation Page Form ApprovedOMB No. 0704-0188...00-2011 4. TITLE AND SUBTITLE Hexavalent Chromium Minimization Strategy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

Heavy metal pollution among autoworkers. II. Cadmium, chromium, copper, manganese, and nickel

Energy Technology Data Exchange (ETDEWEB)

Clausen, J.; Rastogi, S.C.

1977-08-01

Garages and auto-repair workshops may be polluted with other heavy metals besides lead. Blood of autoworkers with high lead content was analyzed for cadmium, chromium, copper, manganese, nickel, ALAD activity and carboxyhaemoglobin level. Cadmium and copper levels in blood of autoworkers were comparable with those of the control subjects while chromium and nickel levels were significantly higher (P < 0.01 for both metals), and scattered raised values of manganese were found. There was no significant mutual correlation between levels of various heavy metals determined in whole blood. High copper levels were slightly related to decreasing ALAD activity (P < 0.1). Nineteen percent of autoworkers were found to have an abnormally high blood level of carboxyhemoglobin. The amount of particulate heavy metal in autoworkshop air was not related to biochemical abnormalities found in the autoworkers. Various sources of pollution of these heavy metals in autoworkshops are discussed.

Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

Directory of Open Access Journals (Sweden)

Anđelković Darko H.

2012-01-01

Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

Determination of the chromium content of laboratory rabbit skeletal muscles by neutron activation analysis

International Nuclear Information System (INIS)

Lux, F.; Trebert Haeberlin, S.; Erhardt, W.

1986-01-01

The chromium content of skeletal muscle of laboratory rabbits has been determined using neutron activation analysis. The procedure for separation of 51 Cr by distillation of chromium oxychloride, described in the literature, has been improved. The arrangements necessary to minimize the chromium blank values are described. The main component of this blank is caused by the residual chromium contamination of the surface of the sample vial; typical values of this component are 0.049 ng Cr (without lyophilization) and 0.12 ng Cr (with lyophilization). The analyses of standard reference materials (SRM) yielded values of the chromium contents that are in agreement (I) with the certified value in the case of NBS Citrus Leaves, and (II) with the latest published value of 9.2+-2.5 ng/g in the case of IAEA animals muscle (H-4). NBS Orchard Leaves was found not to be an appropriate SRM for testing the method. In analyses of samples of thigh muscle of bastard rabbits chromium contents of 6.2-22.9 ng/g (fresh weight basis) were obtained. Comparison of these data with a previously found value of 1.2 ng/g, the literature value [de

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

International Nuclear Information System (INIS)

Smith, W.H.; Purdy, G.

1994-01-01

According to the measurements made in this study, the only situation in which chromium (+6) could exist in a plutonium process solution is one in which a feed containing chromium is dissolved in a glass pot dissolver in high nitric acid concentration and at high temperature. But when the resulting feed is prepared for ion exchange, the chemical treatment reduces chromium to the +3 state. Any solution being processed through the evaporator will only contain chromium in the +3 state and any chromium salts remaining in the evaporator bottoms will be chromium +3 salts

Mechanisms of bands and spirals formation during the drying of watery solutions of mercury (II) chloride with agar-agar

International Nuclear Information System (INIS)

Suarez-DomInguez, Edgardo Jonathan; Betancourt-Mar, Juvencio Alberto

2005-01-01

It is proposed two mechanisms to explain the formation of periodic and non periodic bands and spirals as thin films of gelatinous aqueous solutions of mercury (II) chloride are dried. The first mechanism supposes an homogeneous drying, where the height of the film decreases at constant rate, forming Liesegang bands. The second mechanism implies a non homogeneous drying where an evaporation front drives the formation of periodic bands and spirals

Carcinogenicity and mutagenicity of chromium.

Science.gov (United States)

Léonard, A; Lauwerys, R R

1980-11-01

Occupational exposure represents the main source of human contamination by chromium. For non-occupationally exposed people the major environmental exposure to chromium occurs as a consequence of its presence in food. Chromium must be considered as an essential element. Its deficiency impairs glucose metabolism. Trivalent chromium salts are poorly absorbed through the gastro-intestinal and respiratory tracts because they do not cross membranes easily. Hexavalent chromium can be absorbed by the oral and pulmonary routes and probably also through the skin. After its absorption, hexavalent chromium is rapidly reduced to the trivalent form which is probably the only form to be found in biological material. Epidemiological studies have shown that some chromium salts (mainly the slightly soluble hexavalent salts) are carcinogens. Lung cancers have, indeed, often been reported among workers in chromate-producing industry and, to a lesser extent, in workers from the chrome-pigment industry. The first attempts to produce cancers in experimental animals by inhalation or parenteral introduction gave negative or equivocal results but, from 1960, positive results have been obtained with various chromium compounds. As for the carcinogenic activity, the mutagenicity of chromium has mainly been found with hexavalent salts. In the majority of assay systems used, trivalent chromium appears inactive. It can be considered as evident, however, that the ultimate mutagen which binds to the genetic material is the trivalent form produced intracellularly from hexavalent chromium, the apparent lack of activity of the trivalent form being due to its poor cellular uptake.

Citric-acid preacidification enhanced electrokinetic remediation for removal of chromium from chromium-residue-contaminated soil.

Science.gov (United States)

Meng, Fansheng; Xue, Hao; Wang, Yeyao; Zheng, Binghui; Wang, Juling

2018-02-01

Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

Chromium carcinogenicity: California strategies.

Science.gov (United States)

Alexeeff, G V; Satin, K; Painter, P; Zeise, L; Popejoy, C; Murchison, G

1989-10-01

Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route.

Determination of chromium combined with DNA, RNA and proteins in chromium-rich brewer's yeast by NAA

International Nuclear Information System (INIS)

Ding, W.J.; Qian, Q.F.; Hou, X.L.; Feng, W.Y.; Chai, Z.F.

2000-01-01

The content of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast was determined by neutron activation analysis (NAA). Our results show that the extracted relative amounts and concentrations of DNA, RNA and proteins have no significant difference for two types of yeast, but the chromium content in DNA, RNA and proteins fractions extracted from the chromium-rich yeast are substantially higher than those from the normal. In addition, the concentration of chromium in DNA is much higher than that in RNA and proteins. It is evident that the inorganic chromium compounds can enter the yeast cell during the yeast cultivation in the chromium-containing culture medium and are converted into organic chromium species, which are combined with DNA, RNA and proteins. (author)

Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

DEFF Research Database (Denmark)

Gammelgaard, Bente; Jøns, O; Nielsen, B

1992-01-01

A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both...

Fulltext PDF

Indian Academy of Sciences (India)

Colour Reactions of Co (II). Many salts and complexes of transition metals have bright and attractive colours. ... chromium chloride, copper sulfate, potassium ferrocyanide are ... Procedure: Dissolve 3.0 g of CoClz.6HzO in water to make 25.

Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal.

Science.gov (United States)

Korak, Julie A; Huggins, Richard; Arias-Paic, Miguel

2017-07-01

Due to stricter regulations, some drinking water utilities must implement additional treatment processes to meet potable water standards for hexavalent chromium (Cr(VI)), such as the California limit of 10 μg/L. Strong base anion exchange is effective for Cr(VI) removal, but efficient resin regeneration and waste minimization are important for operational, economic and environmental considerations. This study compared multiple regeneration methods on pilot-scale columns on the basis of regeneration efficiency, waste production and salt usage. A conventional 1-Stage regeneration using 2 N sodium chloride (NaCl) was compared to 1) a 2-Stage process with 0.2 N NaCl followed by 2 N NaCl and 2) a mixed regenerant solution with 2 N NaCl and 0.2 N sodium bicarbonate. All methods eluted similar cumulative amounts of chromium with 2 N NaCl. The 2-Stage process eluted an additional 20-30% of chromium in the 0.2 N fraction, but total resin capacity is unaffected if this fraction is recycled to the ion exchange headworks. The 2-Stage approach selectively eluted bicarbonate and sulfate with 0.2 N NaCl before regeneration using 2 N NaCl. Regeneration approach impacted the elution efficiency of both uranium and vanadium. Regeneration without co-eluting sulfate and bicarbonate led to incomplete uranium elution and potential formation of insoluble uranium hydroxides that could lead to long-term resin fouling, decreased capacity and render the resin a low-level radioactive solid waste. Partial vanadium elution occurred during regeneration due to co-eluting sulfate suppressing vanadium release. Waste production and salt usage were comparable for the 1- and 2-Stage regeneration processes with similar operational setpoints with respect to chromium or nitrate elution. Published by Elsevier Ltd.

Characteristics of chromium-allergic dermatitis patients prior to regulatory intervention for chromium in leather

DEFF Research Database (Denmark)

Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus

2014-01-01

BACKGROUND: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states. OBJECTIVES: To characterize patients...... with chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather. METHODS: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched...... control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations. RESULTS: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather...

Specification for corrosion-resisting chromium and chromium-nickel steel welding rods and bare electrodes - approved 1969

International Nuclear Information System (INIS)

Anon.

1975-01-01

This specification covers corrosion-resisting chromium and chromium-nickel steel welding rods for use with the atomic hydrogen and gas-tungsten-arc welding processes and bare electrodes for use with the submerged arc and gas metal-arc welding processes. These welding rods and electrodes include those alloy steels designated as corrosion- or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4% and nickel does not exceed 50%

Chemical Process for Treatment of Tellurium and Chromium Liquid Waste from I-131 Radioisotope Production

International Nuclear Information System (INIS)

Zainus-Salimin; Gunandjar; Dedy-Harsono; Hendro; Sugeng-Purnomo; Mohammad-Faruq; Zulfakhri

2000-01-01

The I-131 radioisotope is used in nuclear medicine for diagnosis and therapy. The I-131 radioisotope is produced by wet distillation at Bandung Nuclear Research Center and generated about 4,875 Itr of liquid waste containing 2,532.8 ppm of tellurium and 1,451.8 ppm chromium at pH 1. Considering its negative impact to the environment caused by toxic behaviour of tellurium and chromium, it is necessary to treat chemically that's liquid waste. The research of chemical treatment of tellurium and chromium liquid waste from I-131 radioisotope production has been done. The steps of process are involved of neutralisation with NaOH, coagulation-flocculation process for step I using Ca(OH) 2 coagulant for precipitation of sulphate, sulphite, oxalic, chrome Cr 3+ , and coagulation-flocculation process for step II using BaCI 2 coagulant for precipitation of chrome Cr 6+ and tellurium from the supernatant of coagulation in step I. The best result of experiment was achieved at 0.0161 ppm of chromium concentration on the supernatant from coagulation-flocculation of step I using 3.5 g Ca(OH) 2 for 100 ml of liquid waste, and 0.95 ppm of tellurium concentration on the final supernatant from coagulation-flocculation by of step II using 0.7 g BaCI 2 for supernatant from coagulation of step I. (author)

Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II) chloride modified by humic (fulvo-) acid

OpenAIRE

Zhaksyntay Kairbekov; Dina Akbayeva; Zh. Eshova

2012-01-01

It was established that in mild conditions (50-70 oC, РО2= 1 atm) white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II) chloride modified by humic (fulvo-) acid to give mainly phosphoric acid. Humic (fulvo-) acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final ...

Synthesis, crystal structure and anticancer activity of tetrakis(N-isopropylimidazolidine-2-selenone)platinum(II) chloride

Science.gov (United States)

Ahmad, Saeed; Altoum, Ali Osman S.; Vančo, Ján; Křikavová, Radka; Trávníček, Zdeněk; Dvořák, Zdeněk; Altaf, Muhammad; Sohail, Manzar; Isab, Anvarhusein A.

2018-01-01

A Platinum(II) complex of N-isopropylimidazolidine-2-selenone (i-PrImSe), [Pt(i-PrImSe)4]Cl2 (1) was prepared and characterized by elemental analysis, IR and NMR (1H, 13C, 77Se &195Pt) spectroscopy, and X-ray crystallography. The structure of 1 consists of [Pt(i-PrImSe)4]2+ complex ion and chloride counter ions. The platinum(II) atom adopts a distorted square planar geometry. The in vitro antitumor activity of 1 as well as cisplatin, was evaluated by MTT assay against human; ovarian carcinoma A2780 and its cisplatin-resistant subline A2780R, prostate cancer 22Rv1 and breast cancer MCF-7 cell lines. The title complex displayed the activity against the A2780 cells (IC50 = 30.8 μM) at the level comparable to cisplatin (IC50 = 26.8 μM). The interaction studies with sulfur-containing biomolecules revealed its ability to form a variety of intermediates and oxidized species with L-cysteine and reduced glutathione.

Hexavalent Chromium Compounds

Science.gov (United States)

Learn about chromium, exposure to which can increase your risk of lung cancer and cancer of the paranasal sinuses and nasal cavity. Hexavalent chromium compounds have been used as corrosion inhibitors in a wide variety of products and processes.

Determination of HCl and VOC Emission from Thermal Degradation of PVC in the Absence and Presence of Copper, Copper(II Oxide and Copper(II Chloride

Directory of Open Access Journals (Sweden)

Ahamad J. Jafari

2009-01-01

Full Text Available Polyvinyl chloride (PVC has played a key role in the development of the plastic industry over the past 40 years. Thermal degradation of PVC leads to formation of many toxic pollutants such as HCl, aromatic and volatile organic carbon vapors. Thermal degradation of PVC and PVC in the present of copper, cupric oxide and copper(II chloride were investigated in this study using a laboratory scale electrical furnace. HCl and Cl- ion were analyzed by a Dionex ion chromatograph and VOCs compounds were analyzed using GC or GC-MS. The results showed that HCl plus Cl- ion and benzene formed about 99% and 80% respectively in the first step of thermal degradation under air atmosphere. The presence of cupric oxide increases the percentage of short chain hydrocarbons more than 184% and decreases the amount of the major aromatic hydrocarbon and HCl plus Cl- ion to 90% and 65% respectively. The total aromatic hydrocarbon emitted less than when atmosphere was air and difference was statistically significant (Pvalue<0.000

Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

Energy Technology Data Exchange (ETDEWEB)

Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

2014-12-01

Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

Treatment of chromium contaminated soil using bioremediation

Science.gov (United States)

Purwanti, Ipung Fitri; Putri, Tesya Paramita; Kurniawan, Setyo Budi

2017-11-01

Chromium contamination in soil occurs due to the disposal of chromium industrial wastewater or sludge that excess the quality standard. Chromium concentration in soil is ranged between 1 to 300 mg/kg while the maximum health standard is 2.5 mg/kg. Bioremediation is one of technology that could be used for remediating heavy metal contamination in soil. Bacteria have an ability to remove heavy metal from soil. One bacteria species that capable to remove chromium from soil is Bacillus subtilis. The aim of this research was to know the chromium removal percentage in contaminated soil by Bacillus subtilis. Artificial chromium contaminated soil was used by mixing 425gram sand and chromium trichloride solution. Concentration of chromium added into the spiked soil were 50, 75, and 100 mg/L. During 14 days, pH, soil temperature and soil moisture were tested. Initial and final number of bacterial colony and chromium concentration analysed. The result showed that the highest percentage of chromium removal was 11% at a chromium concentration of 75 mg/L

Retention of chromium by modified Al-Bentonite Retenção de cromo por Al-bentonita modificada

Directory of Open Access Journals (Sweden)

C. Volzone

2002-09-01

Full Text Available Retention of chromium (III from a tanning wastewater by modified Al-bentonites was studied. One bentonite from San Juan province, Argentina, was used. Al-bentonite was prepared by contact of bentonite with hydrolyzed OH-Al solutions (0.10 M in Al for 24 hours. The modified Al-bentonites were obtained by: a treatment with 0.5 M sodium chloride; b with 0.5 M sodium chloride adjusted at pH 8; and c treatment with an hexametaphosphate solution after sodium addition. Then, the samples were dried at 100 °C and heated at 500 °C. The chromium (III retention by samples was carried out in batch system putting in contact the material with a 2000 ppm Cr tannery waste at different times. The retained chromium was characterized by analyzing the supernatant using UV-visible spectroscopy. The different chromium retention was correlated with structural characteristics of the solids.Foi estudada a retenção de cromo (III de águas residuais por meio de Al-bentonitas modificadas. Foi usada uma bentonita da província de San Juan, Argentina. As bentonitas-Al forma preparadas colocando-as em contato com soluções (0,10 M Al hydrolizadas de OH-Al durante 24 horas. As bentonitas-Al modidicadas foram obtidas por meio de: a tratamento com cloreto de sódio 0,5 M; b com cloreto de sódio 0,5 M sodium com pH ajustado para 8; e c tratamento com uma solução de hexametafosfato após a adição de sódio. As amostras foram então secas a 100 °C e aquecidas a 500 °C. A retenção do cromo (III pelas amostras foi feita em lotes colocando o material em contato em diferentes tempos com um resíduo contendo 2000 ppm de cromo. O cromo retido foi caracterizado por meio de análise do sobrenadante usando espectroscopia UV-visível. As diferentes retenções de cromo foram correlacionadas com características estruturais dos sólidos.

Reaction of Oxygen with Chromium and Chromium Carbide at Low O2 Pressures and High Temperatures

International Nuclear Information System (INIS)

Hur, Dong O.; Kang, Sung G.; Paik, Young N.

1984-01-01

The oxidation rate of chromium carbide has been measured continuously using thermogravimetric analysis at different oxygen pressures ranging from 1.33x10 -2 to 2.67x10 -1 Pa O 2 at 1000-1300 .deg. C. The oxidation of pure chromium has also been studied between 1000-1300 .deg. C under 6.67x10 -2 Pa O 2 and compared with that of chromium carbide. The oxidation of chromium carbide showed a linear behavior which was different from that of chromium. The oxidation rate of chromium carbide increased with increasing temperature and oxygen pressure was lower than of pure chromium. Above 1200 .deg. C, the volatile oxide was formed and evaporated causing a weight loss. The compositions and morphology of the oxide were studied with X-ray diffractometer and scanning electron microscope, respectively. The morphology of oxide changed with varying temperature and pressure. The oxide scale was consisted of mainly two different layers of Cr 2 O 3 and CrO, and the properties of oxide scale were correlated with oxidation behavior. The oxide film formed in the above test condition has been detached from the carbide surface. The crack and pore were thought to be from CO gas evolving at the interface of chromium carbide and its oxide and the major factor of the linear behavior of chromium carbide

Ultra low nanowear in novel chromium/amorphous chromium carbide nanocomposite films

Science.gov (United States)

Yate, Luis; Martínez-de-Olcoz, Leyre; Esteve, Joan; Lousa, Arturo

2017-10-01

In this work, we report the first observation of novel nanocomposite thin films consisting of nanocrystalline chromium embedded in an amorphous chromium carbide matrix (nc-Cr/a-CrC) with relatively high hardness (∼22,3 GPa) and ultra low nanowear. The films were deposited onto silicon substrates using a magnetic filtered cathodic arc deposition system at various negative bias voltages, from 50 to 450 V. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) suggested the co-existence of chromium and chromium carbide phases, while high resolution transmission electron microscopy (HRTEM) confirmed the presence of the nc-Cr/a-CrC structure. The friction coefficient measured with the ball-on disk technique and the nanowear results showed a strong correlation between the macro and nano-tribological properties of the samples. These novel nanocomposite films show promising properties as solid lubricant and wear resistant coatings with relatively high hardness, low friction coefficient and ultra low nanowear.

Preparation and characterization of high performance NBR/cobalt (II) chloride coordination composites

Science.gov (United States)

Shang, Peng; Shao, Chengli; Li, Qiqing; Wu, Chifei

2018-02-01

Acrylonitrile-butadiene rubber (NBR) composites filled with Cobalt (II) Chloride (CoCl2) particles were prepared by a solvent dispersion method. Acetone was selected as solvent for NBR and CoCl2. To directly enhance the interaction between NBR and CoCl2, a coordination reaction was generated by hot pressing at 200 °C. Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), and x-ray photoelectron spectroscopy (XPS) were employed to investigate the coordination reaction. Results showed that the coordination reaction occurred between the nitrile groups (-CN) of NBR and cobalt ions (Co2+) of CoCl2. Compared with the properties of pure NBR, the tensile strength of NBR/CoCl2 composites filled with 10 parts per hundreds of rubber (phr) CoCl2 increased 2200%. Scanning electron microscopy (SEM) indicated that the CoCl2 particles were dispersed in the NBR matrix homogeneously. The indistinguishable interface between CoCl2 particles and NBR matrix indicated good compatibility. Additionally, thermogravimetric analysis (TGA) showed that coordination reaction improved heat resistance of NBR matrix.

Crystal growth, characterization and theoretical studies of alkaline earth metal-doped tetrakis(thiourea)nickel(II) chloride.

Science.gov (United States)

Agilandeshwari, R; Muthu, K; Meenatchi, V; Meena, K; Rajasekar, M; Aditya Prasad, A; Meenakshisundaram, S P

2015-02-25

The influence of Sr(II)-doping on the properties of tetrakis(thiourea)nickel(II) chloride (TTNC) has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies of doped specimens confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the Sr(II) are observed by scanning electron microscopy. The incorporation of metal into the host crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The nonlinear optical properties of the doped and undoped specimens were studied. Theoretical calculations were performed using the Density functional theory (DFT) method with B3LYP/LANL2DZ as the basis set. The molecular geometry and vibrational frequencies of TTNC in the ground state were calculated and the observed structural parameters of TTNC are compared with parameters obtained from single crystal X-ray studies. The atomic charge distributions are obtained by Mulliken charge population analysis. The first-order molecular hyperpolarizability, polarizability and dipole moment were derived. Copyright © 2014 Elsevier B.V. All rights reserved.

Chromium(III)-trisoxalate, a versatile building block for luminescent materials

Energy Technology Data Exchange (ETDEWEB)

Milos, Mia [Departement de chimie physique, Universite de Geneve, 30 quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland); Hauser, Andreas, E-mail: andreas.hauser@unige.ch [Departement de chimie physique, Universite de Geneve, 30 quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland)

2013-01-15

Chromium(III)-trisoxalate, [Cr(ox){sub 3}]{sup 3-} (ox=C{sub 2}O{sub 4}{sup 2-}), incorporated into polymeric networks of composition [NaCr(ox){sub 3}][M{sup II}(bpy){sub 3}] and [NaCr(ox){sub 3}][M{sup III}(bpy){sub 3}]ClO{sub 4} (ox=C{sub 2}O{sub 4}{sup 2-}, bpy=2,2 Prime -bipyridine, M{sup II}=Zn, Fe, Ru; M{sup III}=Rh, Cr), results in interesting features ranging from phonon-assisted and resonant energy migration within the R{sub 1} line the {sup 2}E state to persistent spectral side-hole burning via the latter, and manifestations of specific nearest-neighbour {pi}-{pi} interactions between bipyridine and oxalate. - Highlights: Black-Right-Pointing-Pointer We present the multifaceted photophysical behaviour of chromium(III)-tris-oxalate. Black-Right-Pointing-Pointer We differentiate between phonon-assisted and resonant energy migration. Black-Right-Pointing-Pointer Resonant energy migration results in spectral diffusion. Black-Right-Pointing-Pointer Resonant energy transfer can be tuned via pressure dependant spectral overlap. Black-Right-Pointing-Pointer {pi}-{pi} interactions with the second coordination sphere create specific spectroscopic sites.

Diminishing Chromium Use on Combined Chromium-Gambier Tanning Process Upon the Characteristics of Tanned Leather

Directory of Open Access Journals (Sweden)

A. Kasim

2014-04-01

Full Text Available The research was aimed to investigate the influence of minimizing chromium use on combined chromium-gambier process upon the characteristics of tanned leather. At the first stage of tanning process, chromium was used and in the second stage it was replaced by gambier. The raw material used was dried saline-preserved goat skin. The treatments applied on the tanning process were the different concentrations of chromium ranging from the highest level of 6% to the lowest level of 1% which was then re-tanned by using 8% concentration of gambier. The examination parameters included chemical and physical properties as well as visual investigation on the tanned leather in accordance with SNI-06-0463-1989-A. The result showed that the tanning process by using 2% chromium in the first step and 8% gambier in the second step was a treatment combination producing tanned leather that met the standard. The examination on tanned leather resulted from such treatment showed 56.33% rawhide, 17.45% of bound tannin, 31.22% of tanning level, tensile strength 386.30 kg/cm2, flexibility 31.91%, leather width 1.3 mm, density 0.75 g/cm3, the leather was quite elastic with light brownish color. In conclusion, minimizing the use of chromium in the combined tanning process of chromium and gambier can be implemented to the lowest of 2% chromium concentration and 8% gambier in the first and second step, respectively.

Syntheses and spectroscopic properties of mercury(II) and nickel(II ...

African Journals Online (AJOL)

Mercury(II) complex, [Hg2(BPTU-2H)Cl2] and nickel(II) complex, [Ni(BPTU-H)2] were prepared by reacting Bis(N-phenylthiourea), BPTU, with mercury(II) chloride and nickel(II) acetate respectively. The complexes were characterized by IR, diffuse reflectance, 1H NMR spectra and elemental analysis. BPTU acts as ...

Models for cytochrome P450 prosthetic heme alkylation. Reaction of diazoacetophenone with (tetraphenylporphyrinato)iron(II) chloride

International Nuclear Information System (INIS)

Komives, E.A.; Tew, D.; Olmstead, M.M.; Ortiz de Montellano, P.R.

1988-01-01

The reaction of diazoacetophenone with (tetraphenylporphyrinato)iron(II) yields [N-(2-phenyl-2-oxoethyl)tetraphenylporphyrinato]iron(II) chloride. The structure of this product has been established by spectroscopic methods and by x-ray crystallography. The crystal structure shows that the first carbon of the N-alkyl group is 2.94 angstrom from the iron atom and that the oxygen of the N-alkyl group points away from the iron. No evidence is seen for the Fe-C-N product expected from insertion of the diazo carbon into the metalloporphyrin iron-nitrogen bond or for intermediates in which the oxygen of the N-(2-phenyl-2-oxoethyl) group is coordinated to the iron. These results suggest it is unlikely that carbene-insertion or oxygen-coordinated intermediates will be detected during the N-alkylation of cytochrome P450 by diazo ketones. The results also rationalize the failure to detect iron-chelated enol species during N-alkylation of the prosthetic group of cytochrome P450 by catalytically activated phenylacetylene. 43 references, 5 figures, 4 tables

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

Science.gov (United States)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-04-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

Science.gov (United States)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-06-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Tris(1,10-phenanthroline-κ2N,N′zinc(II chloride 2-phenyl-4-selenazole-5-carboxylate decahydrate

Directory of Open Access Journals (Sweden)

Jin-Bei Shen

2011-02-01

Full Text Available The asymmetric unit of the title salt, [Zn(C12H8N23](C10H6NO2SeCl·10H2O, contains a [Zn(phen3]2+ cation (phen is 1,10-phenanthroline, uncoordinated chloride and 2-phenyl-4-selenazole-5-carboxylate anions and ten uncoordinated water molecules. The central ZnII ion is six-coordinated by six N atoms from three phen ligands in a distorted octahedral geometry. An extensive O—H...O, O—H...N and O—H...Cl hydrogen-bonding network stabilizes the crystal structure.

Chromium-induced skin damage among Taiwanese cement workers.

Science.gov (United States)

Chou, Tzu-Chieh; Wang, Po-Chih; Wu, Jyun-De; Sheu, Shiann-Cherng

2016-10-01

Little research has been done on the relationships between chromium exposure, skin barrier function, and other hygienic habits in cement workers. Our purpose was to investigate chromium-induced skin barrier disruption due to cement exposure among cement workers. One hundred and eight cement workers were recruited in this study. Urinary chromium concentration was used to characterize exposure levels. The biological exposure index was used to separate high and low chromium exposure. Transepidermal water loss (TEWL) was used to assess the skin barrier function. TEWL was significantly increased in workers with high chromium exposure levels than those with low chromium exposure levels (p = 0.048). A positive correlation was also found between urinary chromium concentration and TEWL (R = 0.28, p = 0.004). After adjusting for smoking status and glove use, a significant correlation between urinary chromium concentrations and TEWL remained. Moreover, workers who smoked and had a high chromium exposure had significantly increased TEWL compared to nonsmokers with low chromium exposure (p = 0.01). Skin barrier function of cement workers may have been disrupted by chromium in cement, and smoking might significantly enhance such skin barrier perturbation with chromium exposure. Decreased chromium skin exposure and smoking cessation should be encouraged at work. © The Author(s) 2015.

Exposure to nickel, chromium, or cadmium causes distinct changes in the gene expression patterns of a rat liver derived cell line.

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Matthew G Permenter

Full Text Available Many heavy metals, including nickel (Ni, cadmium (Cd, and chromium (Cr are toxic industrial chemicals with an exposure risk in both occupational and environmental settings that may cause harmful outcomes. While these substances are known to produce adverse health effects leading to disease or health problems, the detailed mechanisms remain unclear. To elucidate the processes involved in the toxicity of nickel, cadmium, and chromium at the molecular level and to perform a comparative analysis, H4-II-E-C3 rat liver-derived cell lines were treated with soluble salts of each metal using concentrations derived from viability assays, and gene expression patterns were determined with DNA microarrays. We identified both common and unique biological responses to exposure to the three metals. Nickel, cadmium, chromium all induced oxidative stress with both similar and unique genes and pathways responding to this stress. Although all three metals are known to be genotoxic, evidence for DNA damage in our study only exists in response to chromium. Nickel induced a hypoxic response as well as inducing genes involved in chromatin structure, perhaps by replacing iron in key proteins. Cadmium distinctly perturbed genes related to endoplasmic reticulum stress and invoked the unfolded protein response leading to apoptosis. With these studies, we have completed the first gene expression comparative analysis of nickel, cadmium, and chromium in H4-II-E-C3 cells.

Laboratory scale studies on removal of chromium from industrial wastes.

Science.gov (United States)

Baig, M A; Mir, Mohsin; Murtaza, Shazad; Bhatti, Zafar I

2003-05-01

Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes, paint pigments, manufacturing units etc. Chromium exists in aqueous systems in both trivalent (Cr(3+)) and hexavalent (Cr(6+)) forms. The hexavalent form is carcinogenic and toxic to aquatic life, whereas Cr(3+) is however comparatively less toxic. This study was undertaken to investigate the total chromium removal from industrial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation. The study was conducted in four phases. In phase I, the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected. As a result, pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively. Phase II showed that lower dose of sodium meta bisulfate was sufficient to obtain 100% efficiency in reducing Cr(6+) to Cr(3+), and it was noted that reaction time had no significance in the whole process. A design curve for reduction process was established which can act as a tool for treatment of industrial effluents. Phase III studies indicated the best pH was 8.5 for precipitation of Cr(3+) to chromium hydroxide by using lime. An efficiency of 100% was achievable and a settling time of 30 minutes produced clear effluent. Finally in Phase IV actual waste samples from chrome tanning and electroplating industries, when precipitated at pH of 12 gave 100% efficiency at a settling time of 30 minutes and confined that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.

On texture formation of chromium electrodeposits

DEFF Research Database (Denmark)

Nielsen, Christian Bergenstof; Leisner, Peter; Horsewell, Andy

1998-01-01

The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been...

Separation of valent forms of chromium (3) and chromium (6) by coprecipitation with iron (3) hydroxide

International Nuclear Information System (INIS)

Nazirmadov, B.; Khamidov, B.O.; Egorova, L.A.

1988-01-01

Soption 9.62x10 -5 mol/l of 51 Cr radioactive isotope in oxidation states 3 and 6 by iron(3) hydroxide in 1 mol/l of KNO 3 and KCl depending on pH medium is investigated. The region of practically total concentration of Cr(3) and Cr(6 + ) (pH=3-6.5) is determined. The results of spectrophotometric investigations, calculational data on distribution of hydroxocation forms of chromium (3) and of chromium (6) anions and sorption by iron (3) hydroxide permit to characterize sorption of chromium forms in different stages of oxidation. The methods of chromium (3) and chromium (6) separation by coprecipitation of iron (3) hydroxide and their precipitation from it is developed on the above foundation

Reduction of hexavalent chromium collected on PVC filters.

Science.gov (United States)

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.

Stabilization and solidification of chromium-contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

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.

Stabilization and solidification of chromium-contaminated soil

International Nuclear Information System (INIS)

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

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

Recovery of Proteins and Chromium Complexes from Chromium – Containing Leather Waste (CCLW

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B. Gutti

2010-08-01

Full Text Available Chromium – Containing Leather Waste (CCLW constitutes an environmental pollution problem to leather industries disposing the waste by landfill. The waste mainly consists of collagen and chromium III complexes. This work is a design of reactors to recover gelatin, polypeptides and chromium from CCLW. The results of the experiment shows that 68% of protein, based on dry weight of leather scraps, could be recovered. Three reactors with a total volume of 18 m3 was designed to handle 10,431 kg of waste generated from the tanning industries.

Glutamine-containing “turn-on” fluorescence sensor for the highly sensitive and selective detection of chromium (III) ion in water

Science.gov (United States)

Zhao, Meili; Ma, Liguo; Zhang, Min; Cao, Weiguang; Yang, Liting; Ma, Li-Jun

2013-12-01

In this study, we reported a new fluorescence sensor for chromium (III) ion, dansyl-L-glutamine (1). The sensor displayed a unique selective fluorescence “turn-on” response to Cr3+ over other common metal ions in water. Notably, 1 still showed a ratiometric response to Cr3+ in UV-vis absorption spectra. The binding mechanism of 1 to Cr3+ was further clarified by using NMR and ESI-MS spectra. The experiment results indicated that the dual-responses of 1 to Cr3+ should attribute to the coordination of deprotonated sulfonamide group with Cr3+ and the protonation of the dimethylamino group due to the coordination of Cr3+ for 1. In addition, two chloride ions also coordinated to the complex of sensor-chromium (III) ion, which further strengthened the conformation of 1-Cr3+.

Metal chloride precursor synthesization of Cu{sub 2}ZnSnS{sub 4} solar cell materials

Energy Technology Data Exchange (ETDEWEB)

Yeh, Min-Yen; Huang, Yu-Fong; Huang, Cheng-Liang; Yang, Chyi-Da [National Kaohsiung Marine University, Kaohsiung, Taiwan (China); Wuu, Dong-Sing [National Chung Hsing University, Taichung, Taiwan (China); Lei, Po-Hsun [National Formosa University, Yunlin, Taiwan (China)

2014-07-15

Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films with kesterite structures were prepared by directly sol-gel synthesizing spin-coated precursors on soda-lime-glass (SLG) substrates. The CZTS precursors were prepared by using solutions of copper (II) chloride, zinc (II) chloride, tin (IV) chloride, and thiourea. The ratio of SnCl{sub 4} in the precursors was found to play a critical role in the synthesization of CZTS. CZTS phases of SnS and SnS{sub 2} were observed in the synthesized films as prepared using precursors with a close to stoichiometric ratio of CuCl{sub 2}:ZnCl{sub 2}:SnCl{sub 4}:CH{sub 4}N{sub 2}S = 4:1:1:8, where SnCl{sub 4} was 1 mol/l. The amounts of the educed SnS and SnS{sub 2} phases observed in the SEM images could be readily reduced by decreasing the volume of SnCl{sub 4} in the mixed solution. With decreasing amount of SnCl{sub 4} from 1 mol/l, the as prepared CZTS reveals a significant improvement in its crystalline properties. In this work, CZTS with an average absorption coefficient and an optical energy gap of over 10{sup 4} cm{sup -1} and ∼1.5 eV, respectively, was obtained using precursors of copper (II) chloride, zinc (II) chloride, tin (IV) chloride, and thiourea mixed in a ratio of 2:1:0.25:8, and it had good crystallinity revealing a Cu-poor composition.

Magnesium analysis. Spectrophotometric determination of chromium

International Nuclear Information System (INIS)

Anon.

Chromium determination in magnesium used in uranium fabrication by magnesiothermics, applicable for chromium content between 2 to 10 ppm. Magnesium is dissolved in sulfuric acid, oxidized by potassium permanganate, the excess of permanganate is eliminated by sodium nitride. Spectrophotometry at 540 nm of the chromium (VI)-diphenylcarbazide complex [fr

The properties of chromium electrodeposited with programmed currents. Part II. Reversing current

Directory of Open Access Journals (Sweden)

TANJA M. KOSTIC

2000-01-01

Full Text Available The electrodeposition of chromium in programmed reversing current (RC, was investigated in the regime of high cathodic current density (77 A dm-2 and anodic current density (55 A dm-2. The ratio of the cathodic and anodic time (60 : 1 was used. Chromium was deposed on a steel substrate from a chromic-sulphuric acid solution, during one hour. Anode and cathode were suited in a system of parallel plates. Basic properties of deposits, like thickness, morphology, microhardness, brightness were examined. Surface distribution of the deposits was obtained from the measurements of the thicknesses of the deposits (between 32 and 67 µm. A ferromagnetic non-destructive method was used in the measurements. Based on the results, graphic models of deposit surface distribution were made. Two ranges of the thickness could be seen on the model (range 1 - average thickness 35.1 µm and range 2 - average thickness 57.81 µm. These results were statisticaly analysed by colums, rows and by the whole surface. For the whole specimens, the average thickness was 45.39 µm with a coefficient of variation of 0.2582. The basic properties of the deposits did not change with a variation of the thickness. Because of this, the coatings deposited with the reversing current could be much more considered reliable in wear and corrosion protection systems than ones deposited by direct current.

Chromium: a review of environmental and occupational toxicology.

Science.gov (United States)

Bencko, V

1985-01-01

The following topics are covered in this brief review on the environmental and occupational toxicology of chromium: occurrence, production and uses of chromium and chromium compounds; experimental toxicology; chromium toxicity for man; hygienic and ecologic aspects of chromium contamination of the environment. The review provides a conclusive evidence which suggests that chromium, especially its hexavalent form, is both toxic and carcinogenic, but its trivalent form is physiologically essential in the metabolism of insulin. It is also emphasized that among the major sources of environmental chromium today are the cement industry and the increasingly widespread use of chromium compounds added as an anticorrosion admixture to a variety of cooling systems, e.g. in large power plants, which may greatly contribute to the overall pollution of outdoor air at the sites.

Chromium: a review of environmental and occupational toxicology

Energy Technology Data Exchange (ETDEWEB)

Bencko, V

1985-01-01

The following topics are covered in this brief review on the environmental and occupational toxicology of chromium: occurrence, production and uses of chromium and chromium compounds; experimental toxicology; chromium toxicity for man; hygienic and ecologic aspects of chromium contamination of the environment. The review provides a conclusive evidence which suggests that chromium, especially its hexavalent form, is both toxic and carcinogenic, but its trivalent form is physiologically essential in the metabolism of insulin. It is also emphasized that among the major sources of environmental chromium today are the cement industry and the increasingly widespread use of chromium compounds added as an anticorrosion admixture to a variety of cooling systems, e.g. in large power plants, which may greatly contribute to the overall pollution of outdoor air at the sites. 108 references.

Assessment of Cadmium (II) and Chromium (VI) removal from aqueous solution using coconut “Cocosnucifera” Coir as biosorbent in batch and fixed-bed column adsorption

International Nuclear Information System (INIS)

Capili, M.L.S.; Escover, J.J.; San Miguel, J.A.N.; Duavis, A.G.; Sucgang, R.J.

2015-01-01

Heavy metals from industrial effluents are considered contaminants and pose various health risks. Coconut coir is an agricultural waste material abundantly found in the Philippines and is a potential biosorbent of heavy metals. The adsorption of cadmium (II) and chromium (VI) in aqueous solutions were studied under different parameters using coconut coir as the adsorbent. The properties of coconut coir such as crystalline and morphological structure, along with the functional groups present were determined using XRD, SEM and FTIR respectively. The effect of solution pH, initial metal ion concentration and adsorbent dose were determined and optimized concentration of each solution was carried out using AAS. XRF was done to prove that the decrease of metal concentration in the solution was due to the adsorption of the coir. The data obtained from the optimum parameter of each metal were fitted to the Freundlich and Langmuir isotherm models as well as Elovich, first-order and second-order Lagergren kinetic models. These parameters were also used for the adsorption column experiment to determine and compare the adsorption capacity of the coir when applied to a continuous process. Removal optimum parameters for cadmium were at pH 4, initial metal ion concentration of 0.2 mg/L and 0.6g adsorbent dose with a removal efficiency of 99.62%. Optimum parameters for chromium were obtained at pH 5, initial metal ion concentration of 1.2 mg/L and 1g adsorbent dose with a removal efficiency 10.52%. The study indicated that coconut coir is significantly effective in the adsorption of cadmium ions in aqueous solutions than chromium ions based on the reported removal efficiency.(author)

Synthesis of chromium containing pigments from chromium galvanic sludges

International Nuclear Information System (INIS)

Andreola, F.; Barbieri, L.; Bondioli, F.; Cannio, M.; Ferrari, A.M.; Lancellotti, I.

2008-01-01

In this work the screening results of the scientific activity conducted on laboratory scale to valorise chromium(III) contained in the galvanic sludge as chromium precursor for ceramic pigments are reported. The valorisation of this waste as a secondary raw material (SRM) is obtained by achievement of thermal and chemical stable crystal structures able to color ceramic material. Two different pigments pink CaCr 0.04 Sn 0.97 SiO 5 and green Ca 3 Cr 2 (SiO 4 ) 3 were synthesized by solid-state reactions using dried Cr sludge as chromium oxide precursor. The obtained pigments were characterized by X-ray diffraction and SEM analysis. Furthermore the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure Cr 2 O 3 . The characterization carried out corroborates the thermal and chemical stability of the synthesized pigments and, especially for the Cr-Sn pink pigment, the powders develop an intense color that is very similar to the color developed by the pigments obtained starting from pure Cr 2 O 3

Chromium(II) Metal–Organic Polyhedra as Highly Porous Materials

Energy Technology Data Exchange (ETDEWEB)

Park, Jinhee; Perry, Zachary; Chen, Ying-Pin; Bae, Jaeyeon; Zhou, Hong-Cai (DGIST); (TAM)

2017-08-10

Herein we report for the first time the synthesis of Cr(II)-based metal–organic polyhedra (MOPs) and the characterization of their porosities. Unlike the isostructural Cu(II)- or Mo(II)-based MOPs, Cr(II)-based MOPs show unusually high gas uptakes and surface areas. The combination of comparatively robust dichromium paddlewheel units (Cr₂ units), cage symmetries, and packing motifs enable these materials to achieve Brunauer–Emmett–Teller surface areas of up to 1000 m²/g. Reducing the aggregation of the Cr(II)-based MOPs upon activation makes their pores more accessible than their Cu(II) or Mo(II) counterparts. Further comparisons of surface areas on a molar (m2/mol cage) rather than gravimetric (m²/g) basis is proposed as a rational method of comparing members of a family of related molecular materials.

Characterization of the Unusual Product from the Reaction between Cobalt(II) Chloride, Ethane-1,2-diamine, and Hydrochloric Acid: An Undergraduate Project Involving an Unknown Metal Complex.

Science.gov (United States)

Curtis, Neil F.; And Others

1986-01-01

Discusses the need for student research-type chemistry projects based upon "unknown" metal complexes. Describes an experiment involving the product from the reaction between cobalt(II) chloride, ethane-1,2-diamine (en) and concentrated hydrochloric acid. Outlines the preparation of the cobalt complex, along with procedure, results and…

Release of nickel and chromium ions in the saliva of patients with fixed orthodontic appliance: An in-vivo study.

Science.gov (United States)

Dwivedi, Anoop; Tikku, Tripti; Khanna, Rohit; Maurya, Rana Pratap; Verma, Geeta; Murthy, R C

2015-01-01

Various components of fixed orthodontic appliances are continuously interacting with saliva and other fluids in the mouth releasing various metal ions including nickel and chromium that can cause damaging effects if their concentration exceeds above the toxic dose. To determine and compare the level of nickel and chromium in the saliva of patients undergoing fixed orthodontic treatment at different time periods. The sample of saliva of 13 patients was taken at different time periods that is: Group 1 (before appliance placement), Group II, III, and IV (after 1-week, 1-month, and 3 months of appliance placement respectively). The fixed appliance comprised of brackets, bands, buccal tubes, lingual sheath, transpalatal arch and wires composed of Ni-Ti and stainless steel. The level of ions was determined using graphite furnace atomic absorption spectro-photometry. The data thus obtained were statistically analyzed using SPSS Statistical Analysis Software (Version 15.0). Level of nickel and chromium in saliva was highest in Group II and lowest in Groups I for both the ions. On comparison among different Groups, it was statistically significant for all the groups (<0.001) except between Group III and Group IV. The release of nickel and chromium was maximum at 1-week and then the level gradually declined. These values were well below the toxic dose of these ions. The results should be viewed with caution in subjects with Ni hypersensitivity.

Responses of endogenous proline in rice seedlings under chromium exposure

Directory of Open Access Journals (Sweden)

X.Z. Yu

2016-12-01

Full Text Available Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI or chromium nitrate chromium (III. Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues of rice seedlings exposed to chromium (III than those in chromium (VI, majority being in roots rather than shoots. Results also showed that the accumulation capacity of chromium by rice seedlings was positively correlated to chromium concentrations supplied in both chromium variants and the accumulation curve depicted an exponential trend in both chromium treatments over the entire period of exposure. Proline assays showed that both chromium variants induced the change of endogenous proline in shoots and roots of rice seedlings. Chromium (VI of 12.8 mg/L increased proline content significantly (p

Chromium depletion from stainless steels during vacuum annealing

International Nuclear Information System (INIS)

Smith, A.F.; Hales, R.

1977-01-01

During selective chromium oxidation of stainless steels the changes in chromium concentration at the metal surface and in the metal have an important bearing on the overall oxidation performance. It has been proposed that an analogue of chromium behaviour during selective oxidation is obtained from volatilisation of chromium during high temperature vacuum annealing. In the present report the evaporation of chromium from 316 type of steel, vacuum annealed at 1,000 0 C, has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that chromium loss from austenitic stainless steels is rate controlled by interdiffusion in the alloy. As predicted the chromium concentration at the metal surface decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in good agreement with the previously derived model apart from an anomalous region near the surface. Here the higher resolution of the neutron activation technique indicated a zone within approximately 2μm of the surface where the chromium concentration decreased more steeply than expected. (orig.) [de

Effect of brewer’s yeast supplementation on serum glucose and lipids in type II diabetic patients with dislipidemia

OpenAIRE

Sh. Ravanshad; H. Khosvani Borujeni; M. Soveid; B. Zeighami

2005-01-01

Background and purpose : Chromium deficiency leads to impaired glucose and lipid metabolism. Chromium supplementation in type II diabetic patients improves glucose and lipid profiles. Organic chromium, such as found in brewer’s yeast, is much better absorbed than inorganic chromium. In this study, the effect of chromium supplementation in the form of brewer’s yeast on glucose and lipid profile of diabetic patients were evaluated.Materials and methods : In a clinical trial study (before and af...

INVESTIGATION OF TRIVALENT CHROMIUM-BASED CONVERSION COATINGS ON ELECTROGALVANISED STEEL

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Célia Regina Tomachuk

2012-12-01

Full Text Available The passivation process of electrogavanised steel is very important, especially for improving of the corrosion protection and the thickness of the layer obtained can further enhance such protection. In the market exists Cr(III‑based thick layers passivation, however, are operated around 60°C. In order to attend market demands a new process with only 20% of the chromium content is developed, which operates at room temperature. The corrosion behavior was investigated through electrochemical impedance spectroscopy technique in chloride solution and accelerated tests in salt spray chamber. The combination of these tests provides a more complete assessment of the behavior against corrosion of layer passivation obtained. The results with respect to appearance, brightness, uniformity, layer thickness and corrosion resistance are similar to those presented by Cr(III based passivation existing market and Cr(VI based conversion treatment.

In vitro and in vivo corrosion evaluation of nickel-chromium- and copper-aluminum-based alloys.

Science.gov (United States)

Benatti, O F; Miranda, W G; Muench, A

2000-09-01

The low resistance to corrosion is the major problem related to the use of copper-aluminum alloys. This in vitro and in vivo study evaluated the corrosion of 2 copper-aluminum alloys (Cu-Al and Cu-Al-Zn) compared with a nickel-chromium alloy. For the in vitro test, specimens were immersed in the following 3 corrosion solutions: artificial saliva, 0.9% sodium chloride, and 1.0% sodium sulfide. For the in vivo test, specimens were embedded in complete dentures, so that one surface was left exposed. The 3 testing sites were (1) close to the oral mucosa (partial self-cleaning site), (2) surface exposed to the oral cavity (self-cleaning site), and (3) specimen bottom surface exposed to the saliva by means of a tunnel-shaped perforation (non-self-cleaning site). Almost no corrosion occurred with the nickel-chromium alloy, for either the in vitro or in vivo test. On the other hand, the 2 copper-aluminum-based alloys exhibited high corrosion in the sulfide solution. These same alloys also underwent high corrosion in non-self-cleaning sites for the in vivo test, although minimal attack was observed in self-cleaning sites. The nickel-chromium alloy presented high resistance to corrosion. Both copper-aluminum alloys showed considerable corrosion in the sulfide solution and clinically in the non-self-cleaning site. However, in self-cleaning sites these 2 alloys did not show substantial corrosion.

Reproductive toxicological aspects of chromium in males

International Nuclear Information System (INIS)

Ernst, E.

1994-01-01

To expand our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and γ-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG)

Anodic and cathodic reactions in molten calcium chloride

International Nuclear Information System (INIS)

Fray, D.J.

2002-01-01

Calcium chloride is a very interesting electrolyte in that it is available, virtually free, in high purity form as a waste product from the chemical industry. It has a very large solubility for oxide ions, far greater than many alkali halides and other divalent halides and has the same toxicity as sodium chloride and also a very high solubility in water. Intuitively, on the passage of current, it is expected that calcium would be deposited at the cathode and chlorine would evolve at the anode. However, if calcium oxide is added to the melt, it is possible to deposit calcium and evolve oxygen containing gases at the anode, making the process far less polluting than when chlorine is evolved. This process is discussed in terms of the addition of calcium to molten lead. Furthermore, these reactions can be altered dramatically depending upon the electrode materials and the other ions dissolved in the calcium chloride. As calcium is only deposited at very negative cathodic potentials, there are several interesting cathodic reactions that can occur and these include the decomposition of the carbonate ion and the ionization of oxygen, sulphur, selenium and tellurium. For example, if an oxide is used as the cathode in molten calcium chloride, the favoured reaction is shown to be the ionization of oxygen O + 2e - → O 2- rather than Ca 2+ + 2 e- → Ca. The oxygen ions dissolve in the salt leaving the metal behind, and this leads to the interesting hypothesis that metal oxides can be reduced directly to the metal purely by the use of electrons. Examples are given for the reduction of titanium dioxide, zirconium dioxide, chromium oxide and niobium oxide and by mixing oxide powders together and reducing the mixed compact, alloys and intermetallic compounds are formed. Preliminary calculations indicate that this new process should be much cheaper than conventional metallothermic reduction for these elements. (author)

Core and Valence Structures in K beta X-ray Emission Spectra of Chromium Materials

NARCIS (Netherlands)

Torres Deluigi, Maria; de Groot, Frank M. F.; Lopez-Diaz, Gaston; Tirao, German; Stutz, Guillermo; Riveros de la Vega, Jose

2014-01-01

We analyze the core and valence transitions in chromium in a series of materials with a number of different ligands and including the oxidation states: Cr-II, Cr-III, Cr-IV, and Cr-VI. To study the core-to-core transitions we employ the CTM4XAS program and investigate the shapes, widths,

Specification for corrosion-resisting chromium and chromium-nickel steel bare and composite metal cored and stranded arc welding electrodes and welding rods

International Nuclear Information System (INIS)

Anon.

1983-01-01

This specification prescribes requirements for corrosion or heat resisting chromium and chromium-nickel steel electrodes and welding rods. These electrodes and welding rods are normally used for arc welding and include those alloy steels designated as corrosion or heat-resisting chromium and chromium-nickel steels, in which chromium exceeds 4.0 percent and nickel does not exceed 50.0 percent

Sorption of Hg(II and Pb(II Ions on Chitosan-Iron(III from Aqueous Solutions: Single and Binary Systems

Directory of Open Access Journals (Sweden)

Byron Lapo

2018-03-01

Full Text Available The present work describes the study of mercury Hg(II and lead Pb(II removal in single and binary component systems into easily prepared chitosan-iron(III bio-composite beads. Scanning electron microscopy and energy-dispersive X-ray (SEM-EDX analysis, Fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA and point of zero charge (pHpzc analysis were carried out. The experimental set covered pH study, single and competitive equilibrium, kinetics, chloride and sulfate effects as well as sorption–desorption cycles. In single systems, the Langmuir nonlinear model fitted the experimental data better than the Freundlich and Sips equations. The sorbent material has more affinity to Hg(II rather than Pb(II ions, the maximum sorption capacities were 1.8 mmol·g−1 and 0.56 mmol·g−1 for Hg(II and Pb(II, respectively. The binary systems data were adjusted with competitive Langmuir isotherm model. The presence of sulfate ions in the multicomponent system [Hg(II-Pb(II] had a lesser impact on the sorption efficiency than did chloride ions, however, the presence of chloride ions improves the selectivity towards Hg(II ions. The bio-based material showed good recovery performance of metal ions along three sorption–desorption cycles.

Stabilization of chromium: an alternative to make safe leathers.

Science.gov (United States)

Gong, Ying; Liu, Xiaoling; Huang, Li; Chen, Wuyong

2010-07-15

In this study, the original causes for hexavalent chromium presence in the leather were first evaluated by ageing of chromium(III) solutions and chrome tanned hide powder (50 degrees C, UV lightening at 340 nm, 0-36 h). The results showed that the trivalent chromium at instable coordination state was easy to convert into hexavalent chromium in high pH environment, and the probability of the oxidation increased in this order: multi-coordinate chromium, mono-coordinate chromium, and free chromium. For this reason, the process for stabilizing chromium in the leather was designed with the specific material, which was mostly consisted of the reducers and the chelating agents. After treated with the developed process, these leathers were aged (50 degrees C, UV irradiance as 0.68 W/m(2) at 340 nm, 0-72 h) to estimate chromium(VI) presence. Hexavalent chromium was not found in these treated leathers even if the leathers were aged for 72 h. Moreover, the physical and mechanical properties for the leathers varied little after treating. In a word, an inherent safe and effective process was proved to avoid the formation of hexavalent chromium in the leather. 2010 Elsevier B.V. All rights reserved.

Nasal manifestations in chromium industry workers.

Science.gov (United States)

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.

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

Science.gov (United States)

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. 2009 Elsevier B.V. All rights reserved.

Beneficiation Of Chromium Waste By Means Of Magnetic And Gravitational Separation

Directory of Open Access Journals (Sweden)

Brożek M.

2015-09-01

Full Text Available The paper presents the results of investigations of chromium recovery from the Cr waste mud, originating in the production of sodium dichromate. The differentiation of physical properties of particles of different contents of chromium and magnesium compounds is a premise for the use of physical separation methods. The investigations were performed on 2 waste samples, taken by random from the waste dump. The investigations of magnetic and gravity concentration for sample I and II were made, respectively. The results of screen and float and sink analyses of sample II indicate that it is possible to obtain Cr- and Mg-enriched products by means of a combined method of separation, i.e. hydraulic classification and, next, gravitational concentration on the shaking table. The concept of gravity concentration of the tested chromium waste was verified in the technical scale on multiboard shaking tables. The advantage of these fittings in relation to laboratory conditions is the possibility of separation of discussed waste without previous classification. The longer time of separation on the industrial shaking table as well as the respective amount of water directed to the process together with feed enabled an exact separation of initial material. The obtained concentrate in such conditions contains from 25 to 35% Cr2O3, depending on the chromium content in the initial waste material. It results from the fractional magnetic analysis of sample I that by means of the magnetic separation it is possible to obtain the magnetic concentrate of Cr2O3 content minimum 20% and, simultaneously, to obtain the non-magnetic product of increased MgO content. The optimum separation conditions regarding the yield and content of Cr2O3 were determined. The highest value of criterion K for the grade of the concentrate containing over 20% of Cr2O3 is obtained when the 10 mm diameter balls and the 1150 kA/m magnetic field intensity are applied. The yield of the concentrate

Effect of carbon and silicon on nitrogen solubility in liquid chromium and iron-chromium alloys

International Nuclear Information System (INIS)

Khyakkinen, V.I.; Bezobrazov, S.V.

1986-01-01

The study is aimed at specifying the role of carbon and silicon in high-chromium melts nitridation processes. It is shown that in high-chromium melts of the Cr-Fe-C system the nitrogen solubility is reduced with the growth of carbon content and in the chromium concentration range of 70-100% at 1873 K and P N 2 =0.1 MPa it is described by the lg[%N] Cr-Fe-C =lg[%N] cr-fe -0.098[%C] equation. While decreasing the temperature the nitrogen solubility in alloys is increased. Silicon essentially decreases the nitrogen solubility in liquid chromium. For the 0-10% silicon concentration range the relation between the equilibrium content of nitrogen and silicon at 1873 K and P N 2 =0.1 MPa is described by the straight line equation [%N] Cr-Si =6.1-0.338 [%Si

Sythesis of rare earth metal - GIC graphite intercalation compound in molten chloride system

International Nuclear Information System (INIS)

Ito, Masafumi; Hagiwara, Rika; Ito, Yasuhiko

1994-01-01

Graphite intercalation compounds of ytterbium and neodymium have been prepared by interacting graphite and metals in molten chlorides. These rare earth metals can be suspended in molten chlorides in the presence of trichlorides via disproportionation reaction RE(0) + RE(III) = 2RE(II) at lower than 300 degC. Carbides-free compounds are obtained in these systems. (author)

Atmospheric pressure chemical vapour deposition of the nitrides and oxynitrides of vanadium, titanium and chromium

International Nuclear Information System (INIS)

Elwin, G.S.

1999-01-01

A study has been made into the atmospheric pressure chemical vapour deposition of nitrides and oxynitrides of vanadium, titanium and chromium. Vanadium tetrachloride, vanadium oxychloride, chromyl chloride and titanium tetrachloride have been used as precursors with ammonia, at different flow conditions and temperatures. Vanadium nitride, vanadium oxynitride, chromium oxynitride, titanium/vanadium nitride and titanium/chromium oxynitride have been deposited as thin films on glass. The APCVD reaction of VCl 4 and ammonia leads to films with general composition VN x O y . By raising the ammonia concentration so that it is in excess (0.42 dm 3 min -1 VCl 4 with 1.0 dm 3 min -1 NH 3 at 500 deg. C) a film has been deposited with the composition VN 0.8 O 0.2 . Further investigation discovered similar elemental compositions could be reached by deposition at 350 deg. C (0.42 dm 3 min -1 VCl 4 with 0.5 dm 3 min -1 NH 3 ), followed by annealing at 650 deg. C, and cooled under a flow of ammonia. Only films formed below 400 deg. C were found to contain carbon or chlorine ( 3 and ammonia also lead to films of composition VN x O y the oxygen to nitrogen ratios depending on the deposition conditions. The reaction Of VOCl 3 (0.42 dm 3 min -1 ) and ammonia (0.2 dm 3 min -1 ) at 500 deg. C lead to a film of composition VN 0. 47O 1.06 . The reaction of VOCl 3 (0.42 dm 3 min -1 ) and ammonia (0.5 dm 3 min -1 ) at 650 deg. C lead to a film of composition VN 0.63 O 0.41 . The reaction of chromyl chloride with excess ammonia led to the formation of chromium oxide (Cr 2 O 3 ) films. Mixed metal films were prepared from the reactions of vanadium tetrachloride, titanium tetrachloride and ammonia to prepare V x Ti y N z and chromyl chloride, titanium tetrachloride and ammonia to form TiCr x O y N z . Both reactions produced the intended mixed coating but it was found that the vanadium / titanium nitride contained around 10 % vanadium whatever the conditions used. Oxygen contamination

Auxiliary Electrodes for Chromium Vapor Sensors

Energy Technology Data Exchange (ETDEWEB)

Fergus, Jeffrey; Shahzad, Moaiz; Britt, Tommy

2018-05-15

Measurement of chromia-containing vapors in solid oxide fuel cell systems is useful for monitoring and addressing cell degradation caused by oxidation of the chomia scale formed on alloys for interconnects and balance-of-plant components. One approach to measuring chromium is to use a solid electrolyte with an auxiliary electrode that relates the partial pressure of the chromium containing species to the mobile species in the electrolyte. One example is YCrO3 which can equilibrate with the chromium containing vapor and yttrium in yttria stabilized zirconia to establish an oxygen activity. Another is Na2CrO4 which can equilibrate with the chromium-containing vapor to establish a sodium activity.

Chromium allergy and dermatitis: prevalence and main findings

DEFF Research Database (Denmark)

Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl

2015-01-01

The history of chromium as an allergen goes back more than a century, and includesan interventional success with national legislation that led to significant changes inthe 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...

21 CFR 73.2327 - Chromium oxide greens.

Science.gov (United States)

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 the...

21 CFR 73.3111 - Chromium oxide greens.

Science.gov (United States)

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. 1308-38-9...

21 CFR 73.2326 - Chromium hydroxide green.

Science.gov (United States)

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 the...

Chromium fate in constructed wetlands treating tannery wastewaters.

Science.gov (United States)

Dotro, Gabriela; Palazolo, Paul; Larsen, Daniel

2009-06-01

Nine experimental wetlands were built to determine chromium partitioning inside systems treating tannery wastewaters. Results showed 5-day biochemical oxygen demand and chromium removals of 95 to 99% and 90 to 99%, respectively. The majority of chromium was found in association with media (96 to 98%), followed by effluents (2.9 to 3.9%), and the least was found in plant parts (0.1%). Chemical speciation modeling of solutions and scanning electron microscope analysis suggest two potential chromium removal mechanisms--sorption/coprecipitation with iron hydroxides or oxyhydroxides and biomass sorption. The release of the majority of chromium in the iron- and organic-bound phases during sequential extractions supports the proposed dominant removal mechanisms. The use of a mixture of peat and gravel resulted in lower removal efficiencies and stronger partitioning in organic phases during sequential extractions. Chromium was efficiently removed by wetlands, retained through chemical and biological processes. Future research will focus on further exploring removal mechanisms and proposing management strategies for the chromium-containing wetland media.

Chromium in potatoes

International Nuclear Information System (INIS)

Stoddard-Gilbert, K.; Blincoe, C.

1989-01-01

Chromium concentration in potatoes was determined, and tubes were labeled either intrinsically or extrinsically with radioactive chromate ( 51 Cr). A labeled chromium complex was isolated from preparations of raw, baked, or fried potatoes and chromatographed on gel permeation media. Potato pulp and peel contained 1.63 and 2.70 μg of Cr/g tissue, respectively. There was no correlation between the two, nor did they respond similarly to changes of variety or locations. No significant differences were apparent in relative migration of the isolated complexes except between raw and cooked extrinsically labeled preparations

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

Science.gov (United States)

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. Copyright © 2015 Elsevier B.V. All rights reserved.

21 CFR 73.1327 - Chromium oxide greens.

Science.gov (United States)

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 additive...

Interaction of Cr (III), Ni (II), Pb (II) with DTPA complexes of essential metal ions

International Nuclear Information System (INIS)

Gulzar, S.; Zahida; Maqsood, T.; Naqvi, R.R.

2002-01-01

With the increase of anthropogenic activities in the environment, heavy metal toxicity (Chromium, Nickel and Lead) is more common now. DTPA (diethylene triamine pentaacetic acid) a polyamino carboxylic acid is widely used to form hydrophilic and stable complexes with most of the metal ions. In this spectrophotometric study, concentration of Cr(III), Ni(II) and Pb(II) (toxic metal ions) exchanged with Fe(III), Zn(II) and Ca(II) from their DTPA complexes were estimated at pH 4,7 and 9. Concentration of added metal was varied from 1-4 times to that of complexed metal. (author)

Acute and chronic systemic chromium toxicity.

Science.gov (United States)

Gad, S C

1989-10-01

Although chromium and compounds containing it have been recognized as having potential severe adverse effects on health for more than 160 years, understanding of the systemic toxicology and true hazard of these compounds is still not complete. A review of the current state of knowledge is attempted in this paper, with appropriate attention given to the complications of multiple valence states and solubility. Selected chromium compounds, particularly hexavalent ones, are carcinogens, corrosives, delayed contact sensitizers, and have the kidney as their primary target organ. But chromium is also an essential element for humans. The body clearly possesses some effective detoxification mechanisms for some degree of exposure to hexavalent chrome compounds. The significant features of acute and chronic chromium toxicity are presented in view of these considerations.

46 CFR 151.50-34 - Vinyl chloride (vinyl chloride monomer).

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Vinyl chloride (vinyl chloride monomer). 151.50-34... chloride (vinyl chloride monomer). (a) Copper, aluminum, magnesium, mercury, silver, and their alloys shall... equipment that may come in contact with vinyl chloride liquid or vapor. (b) Valves, flanges, and pipe...

Polyvinyl chloride resin

International Nuclear Information System (INIS)

Kim, Hong Jae

1976-06-01

This book contains polyvinyl chloride resin industry with present condition such as plastic industry and polyvinyl chloride in the world and Japan, manufacture of polyvinyl chloride resin ; suspension polymerization and solution polymerization, extruding, injection process, hollow molding vinyl record, vacuum forming, polymer powders process, vinyl chloride varnish, vinyl chloride latex, safety and construction on vinyl chloride. Each chapter has descriptions on of process and kinds of polyvinyl chloride resin.

Establishment of a reference value for chromium in the blood for biological monitoring among occupational chromium workers.

Science.gov (United States)

Li, Ping; Li, Yang; Zhang, Ji; Yu, Shan-Fa; Wang, Zhi-Liang; Jia, Guang

2016-10-01

The concentration of chromium in the blood (CrB) has been confirmed as a biomarker for occupational chromium exposure, but its biological exposure indices (BEIs) are still unclear, so we collected data from the years 2006 and 2008 (Shandong Province, China) to analyze the relationship between the concentration of chromium in the air (CrA) of the workplaces and CrB to establish a reference value of CrB for biological monitoring of occupational workers. The levels of the indicators for nasal injury, kidney (β2 microglobulin (β2-MG)), and genetic damages (8-hydroxy-deoxyguanosine (8-OHdG) and micronucleus (MN)) were measured in all subjects of the year 2011 (Henan Province, China) to verify the protective effect in this reference value of CrB. Compared with the control groups, the concentrations of CrA and CrB in chromium exposed groups were significantly higher (P value of CrB was recommended to 20 μg/L. The levels of nasal injury, β2-MG, 8-OhdG, and MN were not significantly different between the low chromium exposed group (CrB ≤ 20 μg/L) and the control group, while the levels of β2-MG, 8-OHdG, and MN were statistically different in the high chromium exposed group than that in the control group. This research proved that only in occupational workers, CrB could be used as a biomarker to show chromium exposure in the environment. The recommended reference value of CrB was 20 μg/L. © The Author(s) 2015.

21 CFR 73.1326 - Chromium hydroxide green.

Science.gov (United States)

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 (Cr2O3·XH2O...

Μetal Uptake by Sunflower (Helianthus annuus) Irrigated with Water Polluted with Chromium and Nickel.

Science.gov (United States)

Stoikou, Vasiliki; Andrianos, Vangelis; Stasinos, Sotiris; Kostakis, Marios G; Attiti, Sofia; Thomaidis, Nikolaos S; Zabetakis, Ioannis

2017-07-17

The water aquifers of the regions of Asopos River in Viotia and Messapia in Evia (Greece) have been contaminated with hexavalent chromium (Cr (VI)) and bivalent nickel (Ni (II)). Given that these areas are the two biggest tuber producing regions of Greece, in our previous work, the cross-contamination of the food chain with these two heavy metals was quantified. In the present study, the potential of sunflower ( Helianthus annuus ) cultivation in these regions is evaluated. The scope of our study was to investigate the uptake of chromium and nickel by sunflower, in a greenhouse experiment. The study included two cultivation periods of plants in six irrigation lines with different levels of Cr (VI) and Ni (II) ranging from 0 μg/L (control) to 10,000 μg/L. In all plant parts, statistically significant increased levels of Cr (VI) and Ni (II) were found when compared to control ones. Also, a positive correlation, both for Cr and Ni, between levels of heavy metals in irrigation water and plants was observed. Following European Food Safety Authority recommendations, the obtained oil was evaluated as safe for consumption, therefore, sunflower cultivation could be a valid bioremediation solution for the Asopos and Messapia regions.

Chromium Uptake Efficiency of Spinacea olaracea from ...

African Journals Online (AJOL)

The aim of the study was to evaluate the uptake of chromium by Spinacea olaracea and its accumulation in roots and shoots of plants grown in pots at various concentrations of chromium (30, 60, 90,120,150 mg/l). The results revealed that the levels of chromium accumulation in roots and shoots were higher at minimum ...

Inhibiting properties of benzimidazole films for Cu(II)/Cu(I) reduction in chloride media studied by RDE and EQCN techniques

Energy Technology Data Exchange (ETDEWEB)

Scendo, M. [Institute of Chemistry, Saint Cross Academy, ul. Checinska 5, 25020 Kielce (Poland)]. E-mail: scendo@pu.kielce.pl; Hepel, M. [Department of Chemistry, State University of New York, Potsdam, NY 13676, USA (United States)

2007-08-15

The effects of benzimidazole (BIM) and 2-methylbenzimidazole (MBIM) on the electroreduction of Cu(II) on a rotating Pt disk electrode in chloride media were investigated. These studies were undertaken in conjunction with earlier observation that these imidazole derivatives act as inhibitors of copper corrosion processes and are non-toxic. We have found that BIM and MBIM also form adsorption films on Pt, which are able to inhibit one-electron reduction of Cu(II) to Cu(I) and prevent the development of convective diffusion limiting current wave. The inhibition was found to be controlled by field-assisted mass transfer in the film. The ingress of Cu(II) species into the film was detected using the EQCN technique. The EQCN measurements indicate that small fraction of Cu(I) formed in the film by reduction of Cu(II) is retained in the film, most likely in the form of CuCl. The uptake of CuCl by inhibitor films diminishes in strongly inhibiting films (e.g., in acidic medium). The inhibition effectiveness of Cu(II) reduction process by Pt vertical bar BIM and Pt vertical bar MBIM films increases strongly with increasing acidity of the medium in the pH range from 3.0 to 1.0. The mechanism of this remarkable pH effect has been proposed. It is based on charge and pH-induced film restructuring, including changes in orientation and protonation of BIM molecules in the film.

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Substoichiometric determination of chromium by neutron activation analysis

International Nuclear Information System (INIS)

Kudo, K.; Shigematsu, T.; Kobayashi, K.

1977-01-01

A method of radioactivation analysis has been developed for the determination of chromium. It is based on the substoichiometric extraction of chromium diethyldithiocarbamate into methyl-isobutyl-ketone from acetate buffer solution in the presence of EDTA and potassium cyanide. A solution of NaDDC was prepared by dissolving an appropriate amount of GR grade salt in bidistelled water. The concentration of NaDDC was determined by substoichiometric isotope dilution method using 64 Cu or sup(114m)In tracer of known specific activity. The extraction of chromium is not influenced by the presence of EDTA or potassium cyanide while the extraction of chromium is inhibited in tartrate or citrate solution. All metal ions examined are extracted by NaDDC together with chromium and become to interfere for the substoichiometric extraction of chromium. This can be avoided, however, by the addition of EDTA except for copper and silver. The method has been applied for the determination of chromium in high-purity calcium carbonate and NBS glasses as standard reference materials. (T.G.)

Composition of atmospheric precipitation. II. Sulfur, chloride, iodine compounds. Bibliography

Energy Technology Data Exchange (ETDEWEB)

Eriksson, E

1952-01-01

Atmospheric precipitation invariably contains insoluble substances of different origin. A large scale study was conducted to determine the content of sulfur, chloride, and iodine in rainwater from various places around the world. The origin of these elements in rainwater is discussed. Several meteorological factors influence the Cl-content of rainwater. They include: rainfall, wind direction and wind strength, altitude, and seasonal variation.

Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II chloride modified by humic (fulvo- acid

Directory of Open Access Journals (Sweden)

Zhaksyntay Kairbekov

2012-12-01

Full Text Available It was established that in mild conditions (50-70 oC, РО2= 1 atm white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II chloride modified by humic (fulvo- acid to give mainly phosphoric acid. Humic (fulvo- acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final products, optimum conditions of new catalytic reaction of P4 oxidation by oxygen in water medium were defined by kinetics, volumometry, redox-potentiometry, 31Р{1Н} NMR spectroscopy and  titration. 

Corrosion behaviour of high chromium ferritic stainless steels

International Nuclear Information System (INIS)

Kiesheyer, H.; Lennartz, G.; Brandis, H.

1976-01-01

Ferritic steels developed for seawater desalination and containing 20 to 28% chromium, up to 5% Mo and additions of nickel and copper have been tested with respect to their corrosion behaviour, in particular in chloride containing media. The materials in the sensibilized state were tested for intercrystalline corrosion susceptibility in the Strauss-, Streicher-, nitric acid hydrofluoric acid- and Huey-Tests. No intercrystalline corrosion was encountered in the case of the steels with 28% Cr and 2% Mo. The resistance to pitting was assessed on the basis of rupture potentials determined by potentiokinetic tests. The resistance of the steels with 20% Cr and 5% Mo or 28% Cr and 2% Mo is superior to that of the molybdenum containing austenitic types. Addition of nickel yields a significant increase in crevice corrosion resistance; the same applies to resistance in sulfuric acid. In boiling seawater all the materials tested are resistant to stress corrosion cracking. No sign of any type of corrosion was found on nickel containing steels after about 6,000 hours exposure to boiling 50% seawater brine even under salt deposits. (orig.) [de

Kinetics of the oxidative hydroxylation of sodium hypophosphite in the presence of copper (II chloride modified by humic (fulvo- acid

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Zhaksyntay Kairbekov

2012-12-01

Full Text Available It was established that in soft conditions (50-70oC, PO2 = 1 atm sodium hypophosphite effectively is oxidized by oxygen in water solutions of copper(II chloride  to give mainly a phosphorous acid. Humic (fulvo- acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, the intermediate and final products, optimal conditions of new catalytic reaction of NaH2PO2 oxidation by oxygen in water solution were defined by kinetics, volumometry, redox-potentiometry and a titration.

Chromium supplementation improved post-stroke brain infarction and hyperglycemia.

Science.gov (United States)

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.

Cavitation erosion of chromium-manganese and chromium-cobalt coatings processed by laser beam

International Nuclear Information System (INIS)

Giren, B.G.; Szkodo, M.

2002-01-01

In this work the cavitation erosion of chromium-manganese and chromium-cobalt clads were tested, each of them for three cases: (1) without additional processing; (2) after laser heating of the solid state and (3) after laser remelting of the material. Armco iron, carbon steel 45 and chromium-nickel steel 0H18N9T were used as substrates. C.W. CO 2 laser with a beam power of 1000 W was used as a source of radiation. The investigated samples were subjected to cavitation impingement in a rotating disk facility. The results indicate that laser processing of the thick, electrode deposited coatings by laser beam leads in some cases to an increase of their cavitation resistance. Strong dependence of the coatings performance on the substrate, both for the laser processed or unprocessed parts of the materials was also discovered. (author)

Phosphate solubilization and chromium (VI) remediation potential of Klebsiella sp. strain CPSB4 isolated from the chromium contaminated agricultural soil.

Science.gov (United States)

Gupta, Pratishtha; Kumar, Vipin; Usmani, Zeba; Rani, Rupa; Chandra, Avantika

2018-02-01

In this study, an effort was made to identify an efficient phosphate solubilizing bacterial strain from chromium contaminated agricultural soils. Based on the formation of a solubilized halo around the colonies on Pikovskaya's agar amended with chromium (VI), 10 strains were initially screened out. Out of 10, strain CPSB4, which showed significantly high solubilization zone at different chromium concentrations, was selected for further study. The strain CPSB4 showed significant plant growth promotion traits with chromium (VI) stress under in-vitro conditions in broth. The plant growth promotion activities of the strain decreased regularly, but were not completely lost with the increase in concentration of chromium up to 200 mg L -1 . On subjected to FT-IR analysis, the presence of the functional group, indicating the organic acid aiding in phosphate solubilization was identified. At an optimal temperature of 30  ° C and pH 7.0, the strain showed around 93% chromium (VI) reduction under in-vitro conditions in broth study. In soil condition, the maximum chromium (VI) reduction obtained was 95% under in-vitro conditions. The strain CPSB4 was identified as Klebsiella sp. on the basis of morphological, biochemical and 16S rRNA gene sequencing. This study shows that the diverse role of the bacterial strain CPSB4 would be useful in the chromium contaminated soil as a good bioremediation and plant growth promoting agent as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

75 FR 67100 - Superalloy Degassed Chromium From Japan

Science.gov (United States)

2010-11-01

... Chromium From Japan AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on superalloy degassed chromium from Japan. SUMMARY... order on superalloy degassed chromium from Japan would be likely to lead to continuation or recurrence...

Electrochemistry of chromium(0)-aminocarbene complexes

International Nuclear Information System (INIS)

Hoskovcova, Irena; Rohacova, Jana; Meca, Ludek; Tobrman, Tomas; Dvorak, Dalimil; Ludvik, Jiri

2005-01-01

Two series of chromium(0)-(aryl)aminocarbene complexes substituted on the ligand phenyl ring were prepared and electrochemically investigated: pentacarbonyl((N,N-dimethylamino)(phenyl)carbene(chromium(0) (Ia-e) and chelated tetracarbonyl((η 2 -N-allyl-N-allylamino)(phenyl)carbene(chromium(0) (IIa, c-e). For comparison, a tungsten analogue of IIc (III) and a chromium chelate bearing a methyl substituent instead of the phenyl group IV were taken into the study. The intramolecular interactions of p-substituents on the ligand phenyl ring with the reduction and oxidation centres of the molecule of complex (followed electrochemically using LFER [P. Zuman, Substituent Effects in Organic Polarography, Plenum Press, New York, 1967]) enabled to localize the corresponding electron transfer. The influence of the type of coordination, the substituent on the ligand phenyl ring and the central metal atom on oxidation and reduction potentials is discussed

Characterization of TBP containing polysiloxane membrane/insulator/semiconductor structures for hexavalent chromium detection

Energy Technology Data Exchange (ETDEWEB)

Zazoua, A. [Universite de Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria); Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Kherrat, R.; Samar, M.H. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Errachid, A. [Laboratori de Nanobioenginyeria-IBEC, CIBER, Parc Cientific de Barcelona (PCB)-Departament d' Electronica. Universitat de Barcelona, C/Marti i Franques 1, 08028 Barcelona (Spain); Jaffrezic-Renault, N. [LSA - UMR 5180 CNRS - Universite Claude Bernard Lyon 1, 69622 Villeurbanne cedex (France)], E-mail: nicole.jaffrezic@univ-lyon1.fr; Bessueille, F.; Leonard, D. [LSA - UMR 5180 CNRS - Universite Claude Bernard Lyon 1, 69622 Villeurbanne cedex (France)

2008-07-01

A hexavalent chromium-sensitive EMIS sensor (electrolyte membrane insulator semiconductor sensor) is prepared by deposition of a tributylphosphate (TBP) ionophore-containing siloprene membrane on a Si/SiO{sub 2}/Si{sub 3}N{sub 4} structure. The developed EMIS sensor was studied by means of impedance spectroscopy, capacitance-voltage, X-ray photoelectron spectrometry and FT-IR spectroscopy. From the flat-band shift of the EMIS structure, the nersntian response to the anionic species Cr{sub 2}O{sub 7}{sup -} was demonstrated. The linear range of detection is 10{sup -4} M to 10{sup -1} M and the detection limit is 10{sup -5} M. Sulfate and chloride anions are shown not to be interfering whereas carbonate ions present a pK{sup pot} equal to 0.19.

Lipid peroxidation in workers exposed to hexavalent chromium.

Science.gov (United States)

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.

The Chromium is an essential element in the human

International Nuclear Information System (INIS)

Alvarado Gamez, A.; Blanco Saenz, R.; Mora Morales, E.

2002-01-01

The Chromium is an essential element for human and animals, because it a preponderant function in the insulin metabolism as a glucose tolerance factor (GTF). The deficiency of chromium engenders a deterioration in the glucose metabolism due to bad efficiency of insulin. Because the importance of this element an exhaustive reference review was made and this presents some studies realized in laboratory animals and in human beings where it is prove with resuits the effect of chromium over the improvement of patients with non-insulin dependant diabetes. Three substances are presented as chromium active biological forms: a material rich in chromium known as glucose tolerance factor, chromium picolinate and a substance of low molecular weight LMWCr in its forms of apo and holo that contains chromium and it links the insulin receptor and improves its activity. Also this paper presents information about the condition of diabetes in Costa Rica. (Author) [es

Atriopeptin II stimulates chloride secretion in the isolated operculum epithelium of Fundulus heteroclitus

International Nuclear Information System (INIS)

Zadunaisky, J.A.; Scheide, J.I.

1986-01-01

Whole killifish efflux of 36 Cl was increased more than 2x with the addition of 1.4 x 10 -7 M atriopeptin (ANF) to the seawater bath. Atriopeptin II (10 -7 M) added serosally to the isolated Fundulus heteroclitus opercular epithelium resulted in a consistent stimulation of the short-circuit current, from 129.5 +/- 12.3 to 153.5 +/- 13.4 μA/cm 2 . Tissue resistance was decreased 10% from 114.9 +/- 14.2 to 103.9 +/- 11.8 Omega x cm 2 indicating a change in chloride conductance. The effect of ANF was maximal at 10 -7 M and mucosal addition of ANF was ineffective in stimulating the opercular current. The ANF current stimulation did not interfere with the isoproterenol (10 -6 M) response but ANF did not stimulate the current if added after isoproterenol. Serosal addition of propranolol (10 -5 M), sufficient to inhibit 10 -6 M isoproterenol, had no effect on the ANF response. The serosal addition of 10 -6 M tetrodotoxin or 10 -4 M diltiazem did not inhibit the ANF response. The stimulatory effect observed by ANF did not involve the isoproterenol receptor or nerve activation; however, it was a distinct stimulatory response on the isolated opercular epithelium

REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS ...

African Journals Online (AJOL)

a

be used again to adsorb heavy metal ions. ... Among these heavy metals are chromium, copper and ... poisoning can result from high exposure to hexavalent chromium [2]. Most of the ..... At low pH, the sorbent is positively charged because of.

Mixed ligand complexes of alkaline earth metals: Part XII. Mg(II, Ca(II, Sr(II and Ba(II complexes with 5-chlorosalicylaldehyde and salicylaldehyde or hydroxyaromatic ketones

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MITHLESH AGRAWAL

2002-04-01

Full Text Available The reactions of alkaline earth metal chlorides with 5-chlorosalicylaldehyde and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been carried out in 1 : 1 : 1 mole ratio and the mixed ligand complexes of the type MLL’(H2O2 (where M = Mg(II, Ca(II, Sr(II and Ba(II, HL = 5-chlorosalicylaldehyde and HL’ = salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been isolated. These complexes were characterized by TLC, conductance measurements, IR and 1H-NMR spectra.

Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

International Nuclear Information System (INIS)

Lin Feng; Jiang Xianliang; Yu Yueguang; Zeng Keli; Ren Xianjing; Li Zhenduo

2007-01-01

Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured. The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings

Serum chromium levels in gestational diabetes mellitus

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P G Sundararaman

2012-01-01

Full Text Available Objective: To measure serum chromium level in women with gestational diabetes mellitus (GDM from Chennai, South India. Materials and Methods: Thirty women with gestational diabetes, 60 age matched controls. Inclusion criteria: Gestational age 22-28 weeks, age group 20-35 years. Exclusion Criteria: Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer. Results: Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml (P < 0.001. However, there were no significant differences among cases and controls when subdivided by parity. Conclusions: Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

Quantitative determination of chromium in some vegetables in ...

African Journals Online (AJOL)

Chromium has been known to be a micronutrient for mammals for more than four decades. Deficiency in the body results to diabetes, infertility and cardiovascular diseases. However, progress in elucidating the role of chromium has proceeded slowly. Recent studies have shown a potential role of chromium in maintaining ...

Activation of bentonite to remove the chromium from waste water produced by panning industry, and studying the chromium recovery efficiency

International Nuclear Information System (INIS)

Abbasi, S.; Wahba, H.; AL-Masri, M.S.

2010-01-01

The fast development of tanning industry led to an increase in environmental problems resulting from discharging its wastes to the surrounding environment. Thus solving this problem became one of the most important aims that the researchers work on. The chromium content of the industrial water wastes of the tanning industry considered as the main pollutant for the environment. The Aleppo Bentonite is used in early research to remove the chromium from the industrial waste water.The current research aims to find a method to activate the Aleppo Bentonite in order to increase the effective removal of chromium from the industrial waste water which is produced by tanning industry, as well as to specify the optimal conditions for chromium recovery.This study used the Aleppo Bentonite, whose origin is Tal Ajar-Aleppo to study the activation aspects using Sulfuric Acid, Hydrochloric Acid and Nitric Acid, in addition to study the recovery aspects using the same acids and hydrogen peroxide and to specify the optimal conditions for chromium recovery through applying some experiments based on three main factors: concentration, settling time and temperature.It was observed from the applied experiments that it is possible to recover chromium from Bentonite efficiently up to (80% - 90%) by treating the Bentonite with hydrogen peroxide(33% concentration) at room temperature, or by treating it with hydrogen peroxide(8.25% concentration) at 75 o C, while the settling time factor proved that full recovery of chromium is obtained during the first hour, and increasing the time factor does not affect the efficiency of chromium recovery. (author)

Uptake and transport of chromium in plants

International Nuclear Information System (INIS)

Ramachandran, V.; D'souza, T.J.; Mistry, K.B.

1980-01-01

The uptake of chromium, an important soil and water pollutant, by five different plant species was examined in nutrient culture experiments using chromium-51 as a tracer. The concentration in aerial tissues of both trivalent and hexavalent forms of chromium was the greatest in peas followed by beans, tomato and the cereals over identical uptake periods. The uptake of 51 Cr 3+ was, in general, greater than 51 CrO 4 2- . Studies with bean plants indicated that shoot uptake of both forms of chromium decreased with increasing pH and salt concentration of the external solution. Concentrations of 10 -4 M and 10 -5 M DNP inhibited 51 Cr uptake by bean shoots. (author)

Agroindustrial Waste for Lead and Chromium Biosorption

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Susana P. Boeykens

2018-06-01

Full Text Available There is a need to re-evaluate the residues generated in industrial processes for the production of new raw material, reducing the volume of waste. In this regard, the biosorption is a low-cost alternative method for treating effluents compared to conventional methods. The main objectives of this research were: the evaluation of the biosorbent capacity of six waste materials for the extraction of chromium(VI and lead(II ions from aqueous solutions and, the determination of the adsorption and kinetic parameters for the more efficient system. The materials evaluated were: peanut shell (Arachis hypagaea, sugarcane bagasse (Saccharum officinarum, avocado peel (Persea americana, pecan nutshell (Carya illinoinensis, wheat bran (Triticum aestivum and banana peel (Mussa paradisiaca. The highest percentage of lead removal was obtained with wheat bran (89%. For chromium, the percentage was generally much lower compared with lead for all tested biosorbents, the banana peel being the most efficient with a 10% removal. The models that better describe the adsorption processes were: Langmuir and Freundlich. The pseudo-second order kinetic model allowed obtaining the parameters for both systems. The equilibrium time, in both systems, was reached after 60 minutes. The study of Fourier Transformed Infrared spectra and the results of desorption experiments allowed to hypothesize on the mechanisms involved in the adsorption of these metals.

Ductile-brittle transition of thoriated chromium.

Science.gov (United States)

Wilcox, B. A.; Veigel, N. D.; Clauer, A. H.

1972-01-01

Unalloyed chromium and chromium containing approximately 3 wt % ThO2 were prepared from powder produced by a chemical vapor deposition process. When rolled to sheet and tested in tension, it was found that the thoriated material had a lower ductile-to-brittle transition temperature (DBTT) than unalloyed chromium. This ductilizing was evident both in the as-rolled condition and after the materials had been annealed for 1 hour at 1200 C. The improved ductility in thoriated chromium may be associated with several possible mechanisms: (1) particles may disperse slip, such that critical stress or strain concentrations for crack nucleation are more difficult to achieve; (2) particles may act as dislocation sources, thus providing mobile dislocations in this normally source-poor material, in a manner similar to prestraining; and (3) particles in grain boundaries may help to transmit slip across the boundaries, thus relieving stress concentrations and inhibiting crack nucleation.

Thermodynamic properties of chromium bearing slags and minerals. A review

Energy Technology Data Exchange (ETDEWEB)

Xiao Yanping; Holappa, L.

1996-12-31

In this report, the thermodynamic properties of chromium bearing slags and minerals were reviewed based on the available information in the literature. It includes the analysing methods for oxidation state of chromium in slags, oxidation state of chromium and activities of chromium oxides in slags and minerals. The phase diagrams of chromium oxide systems and chromium distributions between slag and metal phases are also covered ill this review. Concerning the analysing methods, it was found that most of the available approaches are limited to iron free slag systems and the sample preparation is very sensitive to the analysing results. In silicate slags under reducing atmosphere, divalent and trivalent chromium co-exist in the slags. It is agreed that the fraction of divalent chromium to total chromium increases with higher temperature, lower slag basicity and oxygen potential. For the slags under oxidising atmosphere, trivalent, pentavalent and hexavalent states were reported to be stable. The activities of CrO and CrO{sub 1.5} were concluded to have positive deviation from ideal solution. Slag basicity has a positive effect and temperature has a negative effect on the activities of chromium oxides. The phase diagrams of the Cr-O, binary, and ternary chromium containing oxide systems have been examined systematically. The analysis shows that the data on the quaternary and quinary systems are insufficient, and require further investigation. The most important features of the chromium containing silicate slags are the large miscibility gaps and the stability of the chromite spinel. (orig.) (76 refs.)

21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining a...

Determination of low chloride values in Rocky Flats scrub alloy solutions and other complex matrices

International Nuclear Information System (INIS)

Holcomb, H.P.

1985-01-01

A turbidimetric method, using silver chloride, has been developed to determine low ppM quantities of chloride in Rocky Flats scrub alloy (RFSA) dissolver solutions. This analytical technique has also been applied to other complex matrices such as process 50% caustic and neutralized Purex low heat liquid waste concentrate. A controlled-pH precipitation with NaOH, during which chloride remains in solution, is used to pretreat samples to minimize salt effects from acids, bases, and/or hydrolyzable ions. Control of pH with bromocresol purple indicator also provides a more consistent pH for silver chloride formation, aiding in turbidity reproducibility. Disodium ethylenediaminetetraacetic acid is employed to negate covalent bonding by Hg(II) with chloride. The average standard deviation was +-17% for turbidity reproducibility in simulated sample aliquots containing a total of 10 to 100 μg chloride. For actual RFSA samples, the relative standard deviation ranged from +-14% to +-26%, depending on initial chloride values. 8 refs., 1 fig

Iodometric determination of peroxydiphosphate in the presence of copper(II) or iron(II) as catalyst.

Science.gov (United States)

Kapoor, S; Sharma, P D; Gupta, Y K

1975-09-01

Peroxydiphosphate can be determined iodometrically in the presence of a large excess of potassium iodide with copper(II) or iron(II) as catalyst through the operation of the Cu(II)/Cu(I) or Fe(II)/Fe(III) cycle. The method is applicable in HClO(4), H(2)SO(4), HCl and CH(3)COOH acid media in the range 0.1-1.0M studied. Nickel, manganese(II), cobalt(II), silver, chloride and phosphate are without effect.

Electrochemical behavior of fission palladium in 1-butyl-3-methylimidazolium chloride

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, M.; Venkatesan, K.A.; Srinivasan, T.G. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2007-08-01

Electrochemical behavior of palladium (II) chloride in 1-butyl-3-methylimidazolium chloride has been investigated by various electrochemical transient techniques using glassy carbon working electrode at different temperatures (343-373 K). Cyclic voltammogram consisted of a prominent reduction wave at -0.61 V (vs. Pd) due to the reduction of Pd(II) to Pd, and two oxidation waves at -0.26 and 0.31 V. A nucleation loop is observed at -0.53 V. The diffusion coefficient of palladium (II) in bmimCl ({proportional_to}10{sup -7} cm{sup 2}/s) was determined and the energy of activation (63 kJ/mol) was deduced from the cyclic voltammograms at various temperatures. Nucleation and growth of palladium on glassy carbon working electrode has been investigated by chronoamperometry and chronopotentiometry. The growth and decay of chronocurrents measured for palladium deposition has been found to follow the instantaneous nucleation model with three-dimensional growth of nuclei. The surface morphology of the deposit obtained at various applied potentials revealed the formation of dendrites immediately after nucleation and spread in all the directions with time. (author)

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

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Nickel or Chromium-Bearing Materials that may be Processed in Exempt Nickel-Chromium Recovery Furnaces XII Appendix XII to Part 266... FACILITIES Pt. 266, App. XII Appendix XII to Part 266—Nickel or Chromium-Bearing Materials that may be...

Chemical Speciation of Chromium in Drilling Muds

International Nuclear Information System (INIS)

Taguchi, Takeyoshi; Yoshii, Mitsuru; Shinoda, Kohzo

2007-01-01

Drilling muds are made of bentonite and other clays, and/or polymers, mixed with water to the desired viscosity. Without the drilling muds, corporations could not drill for oil and gas and we would have hardly any of the fuels and lubricants considered essential for modern industrial civilization. There are hundreds of drilling muds used and some kinds of drilling muds contain chromium. The chemical states of chromium in muds have been studied carefully due to concerns about the environmental influence. However it is difficult to determine the chemical state of chromium in drilling muds directly by conventional analytical methods. We have studied the chemical form of chromium in drilling muds by using a laboratory XAFS system and a synchrotron facility

Combination of synchrotron radiation X-ray microprobe and nuclear microprobe for chromium and chromium oxidation states quantitative mapping in single cells

International Nuclear Information System (INIS)

Ortega, Richard; Deves, Guillaume; Fayard, Barbara; Salome, Murielle; Susini, Jean

2003-01-01

Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation has not been elucidated yet. In this study, chromium oxidation state distribution maps in cells exposed to soluble (Na 2 CrO 4 ), or insoluble (PbCrO 4 ), Cr(VI) compounds have been obtained by use of the ESRF ID-21 X-ray microscope. In addition, the quantitative maps of element distributions in cells have been determined using the nuclear microprobe of Bordeaux-Gradignan. Nuclear microprobe quantitative analysis revealed interesting features on chromium, and lead, cellular uptake. It is suggested that cells can enhance PbCrO 4 solubility, resulting in chromium, but not lead uptake. The differential carcinogenic potential of soluble and insoluble Cr(VI) compounds is discussed with regard to chromium intracellular quantitative distribution

Increased chromium uptake in polymorphonuclear leukocytes from burned patients

International Nuclear Information System (INIS)

Davis, J.M.; Illner, H.; Dineen, P.

1984-01-01

Following thermal injury neutrophil function is severely impaired and thought to be hypometabolic; however, the host is considered to be hypermetabolic. To further investigate the metabolism and the function of neutrophils following thermal injury, neutrophil migration and chromium uptake were studied using radio-labelled neutrophils. Random and directed migration were found to be significantly reduced compared to control values. Neutrophil lysozyme content was also reduced in these burn cells while serum lysozyme from the same patients was significantly elevated over control values. These data suggest lysozyme is released by the neutrophil into the circulatory system. The influx of chromium in cells from burned patients was much greater than the influx in normal cells used in studies for chemotaxis. Influx of chromium over time and over varying concentrations of chromium was linear in cells from burned patients and normals. Cells from burned patients, however, took up more chromium than normals. Influx velocity of chromium was also determined and found to be greater in burn cells than normal cells. Since it has been shown that chromium influx is an energy-dependent reaction it is suggested that cellular energy stores are being depleted by the influx of chromium. Whether this is a response to an intracellular deficit or uncoupling of metabolic pathways is not known at this time

The enriched chromium neutrino source for GALLEX

International Nuclear Information System (INIS)

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

1991-01-01

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

Microscopic analysis of the chromium content in the chromium-induced malignant and premalignant bronchial lesions of the rat

International Nuclear Information System (INIS)

Takahashi, Yuji; Kondo, Kazuya; Ishikawa, Sumiyo; Uchihara, Hiroshi; Fujino, Haruhiko; Sawada, Naruhiko; Miyoshi, Takanori; Sakiyama, Shoji; Izumi, Keisuke; Monden, Yasumasa

2005-01-01

Objective: Our previous studies demonstrated that the frequency of gene instability in lung cancer of chromate workers was very high, but the frequencies of the p53 and ras gene mutations were low. To clarify the carcinogenesis of chromate in the lung, we established a chromate-induced cancer model in the rat proximal airway and examined the relationship between chromium accumulations and the chromium-induced cancer and premalignant bronchial lesions of the rat. Methods: Fifteen male, bred, 12-week-old Jcl-Wister rats were used. A pellet of strontium chromate were inserted into the bronchus of the rats. The rats were sacrificed 9 months after the pellet was inserted. We pathologically examined the region of the bronchi to which the pellet was attached. We quantified the amount of chromium accumulation in the bronchial lesions using a microscopic X-ray fluorescence analyzer. Results: Of the 15 rats, 1 rat had a lesion of squamous cell carcinoma (SCC), 7 rats had carcinoma in situ (CIS) or dysplasia, 8 rats had squamous metaplasia, and 5 rats had goblet cell hyperplasia. The amounts of chromium accumulation in normal epithelium (n=24), goblet cell hyperplasia (n=14), squamous metaplasia (n=8), and dysplasia plus CIS plus SCC (n=9) were 500±1354, 713±1062, 941±1328, and 3511±4473 (mean±SD) counts/s/mA, respectively. The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium (Spearman's correlation coefficient by ranks, rs=0.454, P<0.01). Conclusions: The amount of chromium accumulation was significantly increased according to the progression of malignant change of the bronchial epithelium. Examining the genetic alterations of histologic changes in this model was helpful in elucidating the process of carcinogenesis of chromium in the lung

Roasting and leaching behaviors of vanadium and chromium in calcification roasting-acid leaching of high-chromium vanadium slag

Science.gov (United States)

Wen, Jing; Jiang, Tao; Zhou, Mi; Gao, Hui-yang; Liu, Jia-yi; Xue, Xiang-xin

2018-05-01

Calcification roasting-acid leaching of high-chromium vanadium slag (HCVS) was conducted to elucidate the roasting and leaching behaviors of vanadium and chromium. The effects of the purity of CaO, molar ratio between CaO and V2O5 ( n(CaO)/ n(V2O5)), roasting temperature, holding time, and the heating rate used in the oxidation-calcification processes were investigated. The roasting process and mechanism were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry-differential scanning calorimetry (TG-DSC). The results show that most of vanadium reacted with CaO to generate calcium vanadates and transferred into the leaching liquid, whereas almost all of the chromium remained in the leaching residue in the form of (Fe0.6Cr0.4)2O3. Variation trends of the vanadium and chromium leaching ratios were always opposite because of the competitive reactions of oxidation and calcification between vanadium and chromium with CaO. Moreover, CaO was more likely to combine with vanadium, as further confirmed by thermodynamic analysis. When the HCVS with CaO added in an n(CaO)/ n(V2O5) ratio of 0.5 was roasted in an air atmosphere at a heating rate of 10°C/min from room temperature to 950°C and maintained at this temperature for 60 min, the leaching ratios of vanadium and chromium reached 91.14% and 0.49%, respectively; thus, efficient extraction of vanadium from HCVS was achieved and the leaching residue could be used as a new raw material for the extraction of chromium. Furthermore, the oxidation and calcification reactions of the spinel phases occurred at 592 and 630°C for n(CaO)/ n(V2O5) ratios of 0.5 and 5, respectively.

Evaluation of diatomea algae Thalassiosira weissflogii sensitivity to chloride mercury and methylmercury by chlorophyll fluorescence analysis

Science.gov (United States)

Graevskaya, E. E.; Antal, T. K.; Matorin, D. N.; Voronova, E. N.; Pogosyan, S. I.; Rubin, A. B.

2003-05-01

Measurement of chlorophyll fluorescence has been shown to be a rapid, non-invasive, and reliable method to assess photosynthetic performance in a changing environment. In our study, the pulseamplitude-modulation (PAM) - fluorometric method was used to evaluate the sensitivity to chloride mercury and methylmercury chloride of diatomea microalgae Thalassiosira weissflogii. We found that 10^{-6} and 10^{-7} M MeHg led to a slow decrease in the PS II activity following for prolonged lag phase, whereas the algae was not sensitive to the same concentrations of HgCl2. However observed PS II inactivation by methylmercury was not complete and about 10 percents ofthe cells kept the high level of PS II activity as it was shown by microfluorometric analysis. These cells could determine adaptation of algae to methylmercury effect. Both toxicants decreased the rate of PS II reparation, as well as increased a heat pathway of excitation dissipation in PS II antennae complex.

Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

Science.gov (United States)

Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

2018-02-01

Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor

International Nuclear Information System (INIS)

Arroyo, M.G.; Perez-Herranz, V.; Montanes, M.T.; Garcia-Anton, J.; Guinon, J.L.

2009-01-01

In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H 2 SO 4 . The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe 2+ ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe 3+ ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H 2 SO 4 , the reduction of Cr(VI) to Cr(III) by Fe 2+ ions is preferred, but the coagulation of Fe 3+ and Cr(III) is favoured at the lower H 2 SO 4 concentrations.

Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor

Energy Technology Data Exchange (ETDEWEB)

Arroyo, M.G. [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Perez-Herranz, V., E-mail: vperez@iqn.upv.es [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Montanes, M.T.; Garcia-Anton, J.; Guinon, J.L. [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

2009-09-30

In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H{sub 2}SO{sub 4}. The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe{sup 2+} ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe{sup 3+} ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H{sub 2}SO{sub 4}, the reduction of Cr(VI) to Cr(III) by Fe{sup 2+} ions is preferred, but the coagulation of Fe{sup 3+} and Cr(III) is favoured at the lower H{sub 2}SO{sub 4} concentrations.

Catalytic conversion of cellulose into 5-hydroxymethylfurfural over chromium trichloride in ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Wang, Shui; Du, Yizhen; Zhang, Wenqian; Cheng, Xiaowei; Wang, Jidong [Beijing University of Chemical Technology, Beijing (China)

2014-10-15

An efficient method for converting cellulose into 5-hydroxymethylfurfural (5-HMF) using an inexpensive ionic liquid tetrabutylammonium chloride (TBAC) and relatively low-toxicity catalyst of chromium (Ⅲ) trichloride (CrCl{sub 3}·6H{sub 2}O) was developed. The effects of hydrochloric acid loading, catalyst dosage, reaction temperature and time on the yield of 5-HMF were surveyed to achieve optimal reaction conditions. A 5-HMF yield of 43.7% was obtained within 90 min at 140 .deg. C using oil-bath heating. Glucose and starch were also investigated as feedstock to produce 5-HMF in TBAC/CrCl{sub 3}·6H{sub 2}O system, in which the 5-HMF yield was considerable. After 5-HMF was extracted, TBAC/CrCl{sub 3}·6H{sub 2}O could be used for several runs.

Carcinogenicity of chromium and chemoprevention: a brief update

Directory of Open Access Journals (Sweden)

Wang Y

2017-08-01

Full Text Available Yafei Wang,1,* Hong Su,1,* Yuanliang Gu,1 Xin Song,1 Jinshun Zhao1,2 1Department of Preventative Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, People’s Republic of China; 2Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA *These authors contributed equally to this work Abstract: Chromium has two main valence states: hexavalent chromium (Cr[VI] and trivalent chromium (Cr[III]. Cr(VI, a well-established human carcinogen, can enter cells by way of a sulfate/phosphate anion-transport system, and then be reduced to lower-valence intermediates consisting of pentavalent chromium (Cr[V], tetravalent chromium (Cr[IV] or Cr(III via cellular reductants. These intermediates may directly or indirectly result in DNA damage or DNA–protein cross-links. Although Cr(III complexes cannot pass easily through cell membranes, they have the ability to accumulate around cells to induce cell-surface morphological alteration and result in cell-membrane lipid injuries via disruption of cellular functions and integrity, and finally to cause DNA damage. In recent years, more research, including in vitro, in vivo, and epidemiological studies, has been conducted to evaluate the genotoxicity/carcinogenicity induced by Cr(VI and/or Cr(III compounds. At the same time, various therapeutic agents, especially antioxidants, have been explored through in vitro and in vivo studies for preventing chromium-induced genotoxicity/carcinogenesis. This review aims to provide a brief update on the carcinogenicity of Cr(VI and Cr(III and chemoprevention with different antioxidants. Keywords: hexavalent chromium, Cr(VI, trivalent chromium, Cr(III, genotoxicity, carcinogenicity, chemoprevention, antioxidant 

Cerium(terbium, erbium)chloride-choline chloride aqueous systems

International Nuclear Information System (INIS)

Gajfutdinova, R.K.; Zhuravlev, E.F.; Bikbaeva, G.G.; Domrachev, V.N.; Vanskova, G.I.

1985-01-01

To clarify the effect of rare earth nature on mutual solubility of rare earth salts and amines the solubility of solid phases in the systems, consisting of choline chloride, water and cerium, terbium, erbium chlorides, has been studied. It is established, that solubility isotherms of all the systems, testify to the formation of new solid phases of the composition: Ce(Tb, Er)xCl 3 x2C 5 H 14 ONClx3H 2 O. Individuality of new solid phases is proved by DTA method, the composition is confirmed by chemical analysis and data of PMR spectra, for choline chloride and its complexes with rare earth chlorides of the given composition PMR and IR spectra are studied

Crossover and valence band Kβ X-rays of chromium oxides

International Nuclear Information System (INIS)

Fazinic, Stjepko; Mandic, Luka; Kavcic, Matjaz; Bozicevic, Iva

2011-01-01

Kβ X-ray spectra of chromium metal and selected chromium oxides were measured twice using medium resolution flat crystal spectrometer and high resolution spectrometer employing Johansson geometry after excitation with 2 MeV proton beams. The positions and intensities of crossover (Kβ'') and valence (Kβ 2,5 ) band X-rays relative to the primary Kβ X-ray components were extracted in a consistent way. The results were compared with the existing data obtained by proton and photon induced ionization mechanisms and theoretical predictions. The obtained results in peak relative positions and intensities were analyzed in order to study dependence on the chromium oxidation states and chromium-oxygen bond lengths in selected chromium oxides. Our results obtained by both spectrometers confirm that the linear trend observed for the valence peak relative energy shift as a function of chromium oxidation number does not depend on the experimental resolution. Experimental results for normalized intensities (i.e. relative intensities divided with the number of chromium-oxygen pairs) of crossover and valence band X-rays obtained by both spectrometers are in very good agreement, and follow exponential relationship with the average Cr-O bond lengths in corresponding chromium oxides. The observed trends in crossover and valence X-rays normalized intensities could be used to measure the average chromium-oxygen bond length in various chromium oxides, with the sum of both crossover and valence X-ray normalized intensities being the most sensitive measure.

Preparation of phenacylchloride, morpholinophenacyl and N-Piperidinophenacyl oximes and study of their complexation with Copper (II) and Cobalt (II) ions

International Nuclear Information System (INIS)

Ali, Kamal Eldin Ahmed

1999-01-01

The aim of the present work is to prepare phenacyl chloride oxime and phenacyl of N-Piperidine and morpholine derivatives, and mainly to study their complexes with Cu(II) and Co(II) ions with objective ascertaining that one of these ligands can be used in quantitative extraction of these metal ions from the aqueous solution. Copper (II) salts form 1:1 complexes with the phenyacyl oximes of N-piperidine and morpholine and 1:2 complex with phenacyl chloride oxime. However, cobalt(II) salts form 1:2 complexes with phenacyl oxime of N-piperidine and morpholine but does not complex with phenacyl chloride oxime. The stoichiometry of these complexes were determined by UV/VIS spectrophotometry using the mole ratio, continuous variation and slope ratio methods.The stability constants of the five complexes were calculated from aberrances using Job's method. They showed that the copper (II) and cobalt (II) complexes with N-piperidinophenacy oxime are more stable than those with morpholinophenacyl oxime. Copper (II) complexes with any of these two ligands are more stable than those of cobalt (II). IR spectra of the complexes of copper (II) and cobalt (II) with phenacyl oxime of N-piperidine and morpholine show diminished peaks of hydrogen bonds between N and O atoms of the ligand. Specific extractabilities using amylalcohol of copper (II) complexes with the three ligands increase from PH4 to reach its maximum at PH8. The high value for N-piperidinophenacyl oxime ligand (96%-97%) indicates that, this ligand can be used as analytical reagent for the quantitative spectrophotometric determination of copper (II) salts in aqueous media. Cobalt (II) complexes were formed and extracted from solution only at PH6 (specific PH). The extractabilities ranging from 81.6-87.2% warrants the use of these ligands in quantitative spectrophotometric determination of cobalt (II).(Author)

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

Science.gov (United States)

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

Native Chromium Resistant Staphylococci Species from a Fly Ash ...

African Journals Online (AJOL)

Sixty-six chromium-resistant Staphylococci species belonging to S. epidermidis, S. aureus, S. saprophyticus and S. arlettae were previously isolated from a chromium-polluted Fly ash (FA) dumping site in South Africa. However the genetic mechanisms responsible for chromium resistance were not known. Polymerase chain ...

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

Science.gov (United States)

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 chromium...

Determination of chromium in biological matrices by neutron activation

International Nuclear Information System (INIS)

McClendon, L.T.

1978-01-01

Chromium is recognized to be an essential trace element in several biological systems. It exists in many biological materials in a variety of chemical forms and very low concentration levels which cause problems for many analytical techniques. Both instrumental and destructive neutron activation analysis were used to determine the chromium concentration in Orchard Leaves, SRM 1571, Brewers Yeast, SRM 1569, and Bovine Liver, SRM 1577. Some of the problems inherent with determining chromium in certain biological matrices and the data obtained here at the National Bureau of Standards using this technique are discussed. The results obtained from dissolution of brewers yeast in a closed system as described in the DNAA procedure are in good agreement with the INAA results. The same phenomenon existed in the determination of chromium in bovine liver. The radiochemical procedure described for chromium (DNAA) provides the analyst with a simple, rapid and selective technique for chromium determination in a variety of matrices. (T.G.)

Chloride channels regulate chondrogenesis in chicken mandibular mesenchymal cells.

Science.gov (United States)

Tian, Meiyu; Duan, Yinzhong; Duan, Xiaohong

2010-12-01

Voltage gated chloride channels (ClCs) play an important role in the regulation of intracellular pH and cell volume homeostasis. Mutations of these genes result in genetic diseases with abnormal bone deformation and body size, indicating that ClCs may have a role in chondrogenesis. In the present study, we isolated chicken mandibular mesenchymal cells (CMMC) from Hamburg-Hamilton (HH) stage 26 chick embryos and induced chondrocyte maturation by using ascorbic acid and β-glycerophosphate (AA-BGP). We also determined the effect of the chloride channel inhibitor NPPB [5-nitro-2-(3-phenylpropylamino) benzoic acid] on regulation of growth, differentiation, and gene expression in these cells using MTT and real-time PCR assays. We found that CLCN1 and CLCN3-7 mRNA were expressed in CMMC and NPPB reduced expression of CLCN3, CLCN5, and CLCN7 mRNA in these cells. At the same time, NPPB inhibited the growth of the CMMC, but had no effect on the mRNA level of cyclin D1 and cyclin E (P>0.05) with/without AA-BGP treatment. AA-BGP increased markers for early chondrocyte differentiation including type II collagen, aggrecan (Ptype X collagen. NPPB antagonized AA-BGP-induced expression of type II collagen and aggrecan (Ptype X collagen (PType X collagen might function as a target of chloride channel inhibitors during the differentiation process. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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.

Mode of occurrence of chromium in four US coals

Science.gov (United States)

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.

Chromium speciation in rainwater: temporal variability and atmospheric deposition

Energy Technology Data Exchange (ETDEWEB)

Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry

2002-12-15

Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs.

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

Science.gov (United States)

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. No...

Experimental exposure of healthy subjects with emissions from a gas metal arc welding process--part II: biomonitoring of chromium and nickel.

Science.gov (United States)

Gube, Monika; Brand, Peter; Schettgen, Thomas; Bertram, Jens; Gerards, Kerstin; Reisgen, Uwe; Kraus, Thomas

2013-01-01

The objective of this study was to investigate whether there is a relationship between the external exposure dose of chromium and nickel caused by a metal active gas welding process with a solid high-alloyed steel welding wire and inner exposure of subjects. In order to perform welding fume exposure under controlled and standardized conditions, the investigations were conducted in the "Aachen Workplace Simulation Laboratory". To perform biological monitoring of chromium and nickel, blood and urine samples of 12 healthy male non-smokers who never worked as welders were collected before and after a 6-h exposure to ambient air (0 mg/m(3)) and to welding fumes of a metal active gas welding process once with a concentration of the welding fume of 1 mg/m(3) and once with a concentration of 2.5 mg/m(3). Although the internal exposure to chromium and nickel in this study was comparatively low, the subjects showed significantly increased concentrations of these metals in urine after exposure to welding fume compared to the values at baseline. Moreover, the observed increase was significantly dose dependent for both of the substances. For the biological monitoring of chromium and nickel in urine of subjects exposed to welding fumes, a dependency on exposure dose was seen under standardized conditions after a single exposure over a period of 6 h. Thus, this study contributes to a better understanding of the relationship between ambient and biological exposures from welding fumes and provides a good basis for evaluating future biological threshold values for these metals in welding occupation.

Use of thermogravimetry and thermodynamic calculations for specifying chromium diffusion occurring in alloys containing chromium carbides during high temperature oxidation

International Nuclear Information System (INIS)

Berthod, Patrice; Conrath, Elodie

2015-01-01

The chromium diffusion is of great importance for the high temperature oxidation behaviour of the chromium-rich carbides-strengthened superalloys. These ones contain high chromium quantities for allowing them well resisting hot corrosion by constituting and maintaining a continuous external scale of chromia. Knowing how chromium can diffuse in such alloys is thus very useful for predicting the sustainability of their chromia-forming behaviour. Since Cr diffusion occurs through the external part of the alloy already affected by the previous steps of oxidation (decarburized subsurface) it is more judicious to specify this diffusion during the oxidation process itself. This was successfully carried out in this work in the case of a model chromia-forming nickel-based alloy containing chromium carbides, Ni(bal.)–25Cr–0.5C (in wt.%). This was done by specifying, using real-time thermogravimetry, the mass gain kinetic due to oxidation, and by combining it with the post-mortem determination of the Cr concentration profiles in subsurface. The values of D Cr thus obtained for 1000, 1050 and 1100 °C in the alloy subsurface are consistent with the values obtained in earlier works for similar alloy's chemical compositions. - Highlights: • A Ni25Cr0.50C alloy was oxidized at high temperature in a thermo-balance. • The mass gain files were analysed to specify the Cr 2 O 3 volatilization constant K v . • Concentration profiles were acquired to specify the chromium gradient. • The diffusion coefficient of chromium through the subsurface was deduced. • The obtained diffusion coefficient is consistent with values previously obtained.

FERRATE TREATMENT FOR REMOVING CHROMIUM FROM HIGH-LEVEL RADIOACTIVE TANK WASTE

International Nuclear Information System (INIS)

Sylvester, Paul; Rutherford, Andy; Gonzalez-Martin, Anuncia; Kim, J.; Rapko, Brian M.; Lumetta, Gregg J.

2000-01-01

A method has been developed for removing chromium from alkaline high-level radioactive tank waste. Removing chromium from these wastes is critical in reducing the volume of waste requiring expensive immobilization and deep geologic disposition. The method developed is based on the oxidation of insoluble chromium(III) compounds to soluble chromate using ferrate. The tests conducted with a simulated Hanford tank sludge indicate that the chromium removal with ferrate is more efficient at 5 M NaOH than at 3 M NaOH. Chromium removal increases with increasing Fe(VI)/Cr(III) molar ratio, but the chromium removal tends to level out for Fe(VI)/Cr(III) greater than 10. Increasing temperature leads to better chromium removal, but higher temperatures also led to more rapid ferrate decomposition. Tests with radioactive Hanford tank waste generally confirmed the simulant results. In all cases examined, ferrate enhanced the chromium removal, with a typical removal of around 60-70% of the total chromium present in the washed sludge solids. The ferrate leachate solutions did not contain significant concentrations of transuranic elements, so these solutions could be handled as low-activity waste

[Hexavalent chromium pollution and exposure level in electroplating workplace].

Science.gov (United States)

Zhang, Xu-hui; Zhang, Xuan; Yang, Zhang-ping; Jiang, Cai-xia; Ren, Xiao-bin; Wang, Qiang; Zhu, Yi-min

2012-08-01

To investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure. Field occupational health investigation was conducted in 25 electroplating workplaces. 157 electroplating workers and 93 healthy unexposed controls were recruited. The epidemiological information was collected with face to face interview. Chromium in erythrocytes was determined by graphite furnace atomic absorption spectrophotometer. The median of short-term exposure concentration of chromium in the air at electroplating workplace was 0.06 mg/m(3) (median) and ranging from 0.01 (detect limit) to 0.53 mg/m(3)). The median concentration of Cr (VI) in erythrocytes in electroplating workers was 4.41 (2.50 ∼ 5.29) µg/L, which was significantly higher than that in control subjects [1.54 (0.61 ∼ 2.98) µg/L, P electroplating workers and control subjects, except for the subjects of age less than 30 years old (P = 0.11). There was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards.

The fate of chromium during tropical weathering

DEFF Research Database (Denmark)

Berger, Alfons; Frei, Robert

2014-01-01

We performed a mineral, geochemical and Cr–Sr–Pb isotope study on a laterite profile developed on ca. 540 Ma old tonalitic bedrock in Madagascar with special emphasis on the behavior of chromium during tropical weathering. The observed strong depletions of Ca, Si, and P, and enrichment of Fe and Al...... of a former, positively fractionated and mobile chromium pool has been experimentally constrained in circumneutral and basic leachates of powdered tonalite bedrock where δ53Cr of + 0.21 to + 0.48‰ was measured. Our results show that mobilization of chromium is effective under highly oxidative conditions...

Studies of ion implanted thermally oxidised chromium

International Nuclear Information System (INIS)

Muhl, S.

1977-01-01

The thermal oxidation of 99.99% pure chromium containing precise amounts of foreign elements has been studied and compared to the oxidation of pure chromium. Thirty-three foreign elements including all of the naturally occurring rare earth metals were ion implanted into chromium samples prior to oxidation at 750 0 C in oxygen. The role of radiation induced damage, inherent in this doping technique, has been studied by chromium implantations at various energies and doses. The repair of the damage has been studied by vacuum annealing at temperatures up to 800 0 C prior to oxidation. Many of the implants caused an inhibition of oxidation, the greatest being a 93% reduction for 2 x 10 16 ions/cm 2 of praseodymium. The distribution of the implant was investigated by the use of 2 MeV alpha backscattering and ion microprobe analysis. Differences in the topography and structure of the chromic oxide on and off the implanted area were studied using scanning electron and optical microscopy. X-ray diffraction analysis was used to investigate if a rare earth-chromium compound of a perovskite-type structure had been formed. Lastly, the electrical conductivity of chromic oxide on and off the implanted region was examined at low voltages. (author)

Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium.

Science.gov (United States)

Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

2016-02-23

In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O8(2-) system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01-100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore.

Determination of tracer quantities of chromium in uranium

International Nuclear Information System (INIS)

Huart, A.

1959-01-01

A method is described for the photometric determination of chromium in uranium by absorbency at 540 mμ of the Cr(VI) diphenylcarbazide combination. After attack by nitric acid, the solution is made perchloric, and the chromium oxidised at the boiling point by permanganate. Excess oxidant is removed by hydrochloric acid. Study of operating conditions resulted in a method with an accuracy of ± 0,5 ppm for 0,5 to 15 ppm chromium in the metal. (author) [fr

TEM characterisation of stress corrosion cracks in nickel based alloys: effect of chromium content and chemistry of environment

International Nuclear Information System (INIS)

Delabrouille, F.

2004-11-01

Stress corrosion cracking (SCC) is a damaging mode of alloys used in pressurized water reactors, particularly of nickel based alloys constituting the vapour generator tubes. Cracks appear on both primary and secondary sides of the tubes, and more frequently in locations where the environment is not well defined. SCC sensitivity of nickel based alloys depends of their chromium content, which lead to the replacement of alloy 600 (15 % Cr) by alloy 690 (30 % Cr) but this phenomenon is not yet very well understood. The goal of this thesis is two fold: i) observe the effect of chromium content on corrosion and ii) characterize the effect of environment on the damaging process of GV tubes. For this purpose, one industrial tube and several synthetic alloys - with controlled chromium content - have been studied. Various characterisation techniques were used to study the corrosion products on the surface and within the SCC cracks: SIMS; TEM - FEG: thin foil preparation, HAADF, EELS, EDX. The effect of chromium content and surface preparation on the generalised corrosion was evidenced for synthetic alloys. Moreover, we observed the penetration of oxygen along triple junctions of grain boundaries few micrometers under the free surface. SCC tests show the positive effect of chromium for contents varying from 5 to 30 % wt. Plastic deformation induces a modification of the structure, and thus of the protective character, of the internal chromium rich oxide layer. SCC cracks which developed in different chemical environments were characterised by TEM. The oxides which are formed within the cracks are different from what is observed on the free surface, which reveals a modification of medium and electrochemical conditions in the crack. Finally we were able to evidence some structural characteristics of the corrosion products (in the cracks and on the surface) which turn to be a signature of the chemical environment. (author)

[Occupational exposure to hexavalent chromium during aircraft painting].

Science.gov (United States)

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.

Chromium in Drinking Water: Association with Biomarkers of Exposure and Effect

Science.gov (United States)

Sazakli, Eleni; Villanueva, Cristina M.; Kogevinas, Manolis; Maltezis, Kyriakos; Mouzaki, Athanasia; Leotsinidis, Michalis

2014-01-01

An epidemiological cross-sectional study was conducted in Greece to investigate health outcomes associated with long-term exposure to chromium via drinking water. The study population consisted of 304 participants. Socio-demographics, lifestyle, drinking water intake, dietary habits, occupational and medical history data were recorded through a personal interview. Physical examination and a motor test were carried out on the individuals. Total chromium concentrations were measured in blood and hair of the study subjects. Hematological, biochemical and inflammatory parameters were determined in blood. Chromium in drinking water ranged from Chromium levels in blood (median 0.32 μg·L−1, range chromium exposure dose via drinking water, calculated from the results of the water analyses and the questionnaire data, showed associations with blood and hair chromium levels and certain hematological and biochemical parameters. Groups of subjects whose hematological or biochemical parameters were outside the normal range were not correlated with chromium exposure dose, except for groups of subjects with high triglycerides or low sodium. Motor impairment score was not associated with exposure to chromium. PMID:25268509

Chromium fractionation and speciation in natural waters.

Science.gov (United States)

Pereira, Catarinie Diniz; Techy, João Gabriel; Ganzarolli, Edgard Moreira; Quináia, Sueli Pércio

2012-05-01

It is common for leather industries to dump chromium-contaminated effluent into rivers and other bodies of water. Thus, it is crucial to know the impacts caused by this practice to the environment. A study on chromium partitioning and speciation, with determination at trace levels, was carried out in a potentially contaminated creek. Chromium fractionation and speciation was performed using a flow-injection preconcentration system and detection by flame atomic absorption spectrometry. High levels of this element were found in the particulate material (449-9320 mg kg(-1)), which indicates its compatibility with this fraction. The concentration of Cr(iii) in the water samples collected ranged from 5.2-105.2 μg L(-1). Cr(vi) was always below of the DL (0.3 μg L(-1)). Chromium accumulation observed in the sediment (873-1691 mg kg(-1)) may confirm contamination due to the long term release of contaminated effluents in the creek.

Chromium-induced membrane damage: protective role of ascorbic acid.

Science.gov (United States)

Dey, S K; Nayak, P; Roy, S

2001-07-01

Importance of chromium as environmental toxicant is largely due to impact on the body to produce cellular toxicity. The impact of chromium and their supplementation with ascorbic acid was studied on plasma membrane of liver and kidney in male Wistar rats (80-100 g body weight). It has been observed that the intoxication with chromium (i.p.) at the dose of 0.8 mg/100 g body weight per day for a period of 28 days causes significant increase in the level of cholesterol and decrease in the level of phospholipid of both liver and kidney. The alkaline phosphatase, total ATPase and Na(+)-K(+)-ATPase activities were significantly decreased in both liver and kidney after chromium treatment, except total ATPase activity of kidney. It is suggested that chromium exposure at the present dose and duration induce for the alterations of structure and function of both liver and kidney plasma membrane. Ascorbic acid (i.p. at the dose of 0.5 mg/100 g body weight per day for period of 28 days) supplementation can reduce these structural changes in the plasma membrane of liver and kidney. But the functional changes can not be completely replenished by the ascorbic acid supplementation in response to chromium exposure. So it is also suggested that ascorbic acid (nutritional antioxidant) is useful free radical scavenger to restrain the chromium-induced membrane damage.

Workshop on effects of chromium coating on Nb3Sn superconductor strand: Proceedings

International Nuclear Information System (INIS)

1994-01-01

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 3 Sn strand

Cytokine detection for the diagnosis of chromium allergy*

Science.gov (United States)

Martins, Luis Eduardo Agner Machado; dos Reis, Vitor Manoel Silva

2013-01-01

BACKGROUND Patch testing remains the gold standard method for the identification of the etiologic agent of allergic contact dermatitis. However, it is a subjective, time-consuming exam whose technique demands special care and which presents some contraindications, which hamper its use. In a recent study, we showed that the proliferation assay can suitably replace patch testing for the diagnosis of chromium allergy, which had been previously demonstrated only for nickel allergy. In this study, we try to refine the method by reducing the incubation period of cultures for lymphocyte proliferation assays in response to chromium. OBJECTIVE Develop an alternative or complementary diagnostic test for chromium allergic contact dermatitis. METHODS We compared the production of 9 cytokines (IFN-γ, IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17 and RANTES) between 18 chromium-allergic patients and 19 controls. RESULTS Chromium increased the production of IFN-y, IL-5, IL-2 and IL-13 in allergic patients, but only IL-2 and especially IL-13 helped discriminate allergic patients from controls. The sensitivity, specificity and accuracy found with IL-13 were about 80%. CONCLUSIONS IL-13 and IL-2 detection may be used to diagnose chromium allergy in 2-day cultures. However, in general, the 6-day cultures seem to be superior for this purpose. PMID:24173176

Thermodynamic Properties of Chromium Adsorption by Sediments ...

African Journals Online (AJOL)

MBI

2013-06-19

Jun 19, 2013 ... The adsorption of Chromium from aqueous solution using river Watari sediment as an adsorbent was modeled. The influence of initial ... number of metals, including chromium, copper, nickel and zinc. The ion ... through filter paper to determine the concentration ... liquid and solid phases were separated by.

Chloride ingress prediction

DEFF Research Database (Denmark)

Frederiksen, Jens Mejer; Geiker, Mette Rica

2008-01-01

Prediction of chloride ingress into concrete is an important part of durability design of reinforced concrete structures exposed to chloride containing environment. This paper presents experimentally based design parameters for Portland cement concretes with and without silica fume and fly ash...... in marine atmospheric and submersed South Scandinavian environment. The design parameters are based on sequential measurements of 86 chloride profiles taken over ten years from 13 different types of concrete. The design parameters provide the input for an analytical model for chloride profiles as function...... of depth and time, when both the surface chloride concentration and the diffusion coefficient are allowed to vary in time. The model is presented in a companion paper....

OPTIMIZATION OF NICKEL (II) AND CHROMIUM (III) REMOVAL ...

African Journals Online (AJOL)

RSM)was used to study the effect of three adsorption variables (pH, initial concentration, and adsorbent dosage) in order to determine the optimum process conditions for the adsorptions of Ni (II) and Cr (III) onto sulphuric acid modified sorghum ...

Electronic spectroscopy and ligand-field analysis of cis-carbonato (rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) chromium(III) chloride

International Nuclear Information System (INIS)

Choi, Jong-Ha; Oh, In-Gyung; Linder, Rolf; Schoenherr, Thomas

2004-01-01

The absorption spectra of microcrystalline salts of cis-[Cr(cycb)(O 2 CO)] + (cycb=rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) have been measured between 13,000 and 50,000 cm -1 at temperatures down to 2 K. The vibrational intervals of the electronic ground state were extracted by recording emission and far-IR spectra. The zero-phonon line in the sharp-line absorption spectrum splits into two components by 144 cm -1 . The nine electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the observed transitions, a ligand-field analysis has been performed to probe the ligand-field properties of carbonato group in the chromium(III) complex. It is found that the carbonato oxygen has moderately strong σ- and π-donor properties toward chromium(III) ion

New Evidence against Chromium as an Essential Trace Element.

Science.gov (United States)

Vincent, John B

2017-12-01

Nearly 60 y ago, chromium, as the trivalent ion, was proposed to be an essential element, but the results of new studies indicate that chromium currently can only be considered pharmacologically active and not an essential element. Regardless, articles still continue to appear in the literature claiming chromium is an essential element. Chromium has been marketed as an agent to reduce body mass and develop muscle; however, such marketing claims are no longer allowed in the United States because these claims, similar to claims of essential status, are not supported by experiments. Trivalent chromium has also been proposed as a therapeutic agent to increase insulin sensitivity and affect lipid metabolism. Although effective in certain rodent models, beneficial effects in humans have not been unequivocally established. Molecular mechanisms have been proposed for the beneficial effects but have not been definitively shown to occur in animals. © 2017 American Society for Nutrition.

Corrosion behaviour of porous chromium carbide/oxide based ceramics in supercritical water

International Nuclear Information System (INIS)

Dong, Z.; Xin, T.; Chen, W.; Zheng, W.; Guzonas, D.

2011-01-01

Porous chromium carbide with a high density of open pores was fabricated by a reactive sintering method. Chromium oxide ceramics were obtained by re-oxidizing the porous chromium carbides formed. Some samples were added with yttria at 5 wt. %, prior to reactive sintering to form porous structures. Corrosion tests in SCW were performed at temperatures ranging from 375 o C to 625 o C with a fixed pressure at around 25∼30 MPa. The results show that chromium carbide is stable in SCW environments at temperatures up to 425 o C, above which disintegration of carbides through oxidation occurs. Porous chromium oxide samples show better corrosion resistance than porous chromium carbide, but disintegrate in SCW at around 625 o C. Among all the samples tested, chromium oxide ceramics with added yttria exhibited much better corrosion resistance compared with the pure chromium carbide/oxides. No evidence of weight change or disintegration of porous chromium oxides with 5 wt % added yttria was observed after exposure at 625 o C in SCW for 600 hours. (author)

In vitro metabolism and permeation studies in rat jejunum

DEFF Research Database (Denmark)

Gammelgaard, Bente; Jensen, K; Steffansen, B

1999-01-01

The purpose of these studies was to compare the in vitro absorption of two inorganic chromium(III) compounds: chromium chloride and chromium nitrate, with organic chromium(III)-picolinate; and to investigate if any in vitro metabolism of chromium(VI) takes place. The in vitro metabolism studies...

Chromium Enrichment on P11 Ferritic Steel by Pack Cementation

Directory of Open Access Journals (Sweden)

Fauzi F. A.

2016-01-01

Full Text Available The future thermal power plant is expected to operate at higher temperature to improve its efficiency and to reduce greenhouse gas emission. This target requires better corrosion properties of ferritic steels, which commonly used as materials for superheater and reheater of boiler tubes. In this work, chromium enrichment on the surface of ferritic steel is studied. The deposited chromium is expected to become a reservoir for the formation of chromia protective layer. Chromium was deposited on the substrate of steel by pack cementation process for two hours at the temperature of 850ºC, 950ºC and 1050ºC, respectively. XRD analysis indicated that chromium was successfully deposited at all temperatures. Somehow, SEM cross sectional image showed that continuous layer of chromium was not continuously formed at 850oC. Therefore, this research clarify that chromium enrichment by pack cementation may be conducted at the temperature above 950°C.

Atmospheric deposition of trace elements around point sources and human health risk assessment. II: Uptake of arsenic and chromium by vegetables grown near a wood preservation factory

DEFF Research Database (Denmark)

Larsen, Erik Huusfeldt; Moseholm, Lars; Nielsen, Margot M.

1992-01-01

Kale, lettuce, carrots and potatoes were grown in 20 experimental plots surrounding a wood preservation factory, to investigate the amount and pathways for plant uptake of arsenic and chromium. Arsenate used in the wood preservation process is converted to the more toxic arsenite by incineration...... of waste wood and is emitted into the atmosphere. Elevated concentrations of inorganic arsenic and chromium were found both in the test plants and in the soil around the factory. Multivariate statistical analysis of the results indicated that the dominating pathway of arsenic and chromium from the factory...

Electronic structure of chromium-doped lead telluride-based diluted magnetic semiconductors

International Nuclear Information System (INIS)

Skipetrov, E.P.; Pichugin, N.A.; Slyn'ko, E.I.; Slyn'ko, V.E.

2011-01-01

The crystal structure, composition, galvanomagnetic and oscillatory properties of the Pb 1-x-y Sn x Cr y Te (x = 0, 0.05-0.30, y ≤ 0.01) alloys have been investigated with varying matrix composition and chromium impurity concentration. It is shown that the chromium impurity atoms dissolve in the crystal lattice at least up to 1 mol.%. The following increase of the chromium concentration leads to the appearance of microscopic regions enriched with chromium and inclusions of Cr-Te compounds. A decrease of the hole concentration, a p-n-conversion of the conductivity type and a pinning of the Fermi level by the chromium resonant level are observed with increasing chromium content. Initial rates of changes in the free carrier concentration on doping are determined. The dependences of electron concentration and Fermi level on tin content are calculated by the two-band Kane dispersion relation. A diagram of electronic structure rearrangement for the chromium-doped alloys with varying the matrix composition is proposed.

A solid-state hybrid density functional theory study of Prussian blue analogues and related chlorides at pressure

Energy Technology Data Exchange (ETDEWEB)

Middlemiss, Derek S; Lawton, Lorreta M; Wilson, Chick C [Department of Chemistry and WestCHEM Research School, University Avenue, University of Glasgow, Glasgow G12 8QQ (United Kingdom)], E-mail: c.c.wilson@chem.gla.ac.uk

2008-08-20

The variations with pressure in the structural, electronic and magnetic properties of a series of Prussian blue analogues (PBAs) K{sup I}M{sup II}[Cr{sup III}(CN){sub 6}] (M = V{sup II}, Mn{sup II} and Ni{sup II}) and associated isomorphous chlorides K{sup I}M{sup II}Cr{sup III}Cl{sub 6} are investigated within a series of solid-state hybrid density functional calculations. The sensitivity of the computed properties to the choice of Hamiltonian is tested by application of functionals containing 35%, 65% and 100% admixtures of Fock exchange. Magnetic coupling constants (J) are obtained at a range of cell volumes (V), with fits of the Bloch relationship (J {proportional_to} V{sup -{epsilon}}, {epsilon} typically 3-4) yielding exponents {epsilon} in the ranges 5.16-6.34, 8.48-12.07 and 4.00-4.51 for the antiferromagnetic (AF) V{sup II}Cr{sup III}-, ferrimagnetic (FI) Mn{sup II}Cr{sup III}- and ferromagnetic (FO) Ni{sup II}Cr{sup III} PBAs, respectively; and 3.33-4.99, 1.86-3.09 and 1.65-3.28 for the AF V{sup II}Cr{sup III}-, FO Mn{sup II}Cr{sup III}- and FO Ni{sup II}Cr{sup III} chlorides, respectively. The Mn{sup II}Cr{sup III} PBA range encloses the high values {epsilon}{approx}9-10 obtained in a recent joint experimental and theoretical study, and it is suggested that this strong magnetostructural effect arises due to the presence of competing AF and FO interactions in this material. Estimates of the spin ordering temperatures derived from the combination of the 35%-functional couplings with a mean field approach are in good agreement with experiment in the V{sup II}Cr{sup III} and Ni{sup II}Cr{sup III} PBAs, but are too low in the Mn{sup II}Cr{sup III} system. The variations with pressure in the structural parameters, charges and spin moments are also detailed, the PBA and chloride energy-volume data yielding bulk moduli in the ranges 39-53 and 36-50 GPa, respectively. Finally, the energies governing CN{sup -} ligand isomerization are estimated and successfully

cis,cis,cis-(Acetato-κ2O,O′bis[1,2-bis(diphenylphosphanylethane-κ2P,P′]ruthenium(II 0.75-trifluoromethanesulfonate 0.25-chloride

Directory of Open Access Journals (Sweden)

João Figueira

2013-04-01

Full Text Available In the title RuII carboxylate compound, [Ru(C2H3O2(C26H24P22](CF3O3S0.75Cl0.25, the distorted tris-bidentate octahedral stereochemistry about the RuII atom in the complex cation comprises four P-atom donors from two 1,2-bis(diphenylphosphanylethane ligands [Ru—P = 2.2881 (13–2.3791 (13 Å] and two O-atom donors from the acetate ligand [Ru—O = 2.191 (3 and 2.202 (3 Å]. The disordered counter-anions are located on the same site in the structure in a 3:1 ratio, the expanded formula comprising four complex cations, three trifluoromethanesulfonate anions and one chloride anion, with two such formula units in the unit cell.

Chromium Salen Mediated Alkene Epoxidation

DEFF Research Database (Denmark)

Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.

2002-01-01

The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

Study on Leaching of Hexavalent Chromium from Hardened Concretes Using Tank Leaching Test

OpenAIRE

Takahashi, Shigeru; Sakai, Etsuo; Sugiyama, Takafumi

2007-01-01

Tank leaching tests were carried out to investigate the behavior of leaching trace elements from monolith samples. This study consists of two series, and the trace element used was hexavalent chromium. In Series I, the influence of the leachant/surface area of the specimen (L/S ratio) on the leaching amount was investigated. The leaching amount was found to increase with the amount of worked water. This shows that any L/S ratio can be selected in the tank leaching test. In Series II, th...

Stabilization of chromium salt in ordinary portland cement

Indian Academy of Sciences (India)

Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration.

Coordination behavior of tetraaza [N4] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: Synthesis, spectroscopic characterization and anticancer activity

Science.gov (United States)

El-Boraey, Hanaa A.

2012-11-01

Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N4] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate dx2-y2 ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC50 = 25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

Characteristics of oxidation of low-alloyed chromium in nitrogen tetroxide

International Nuclear Information System (INIS)

Kamenev, A.Ya.; Goncharova, N.V.; Kopets, Z.V.; Tedushin, E.E.

1985-01-01

The effect of N 2 O 4 on corrosion properties of chromium-based alloys is studied. The method of structural materials analysis is described using as an example chromium-based alloys in the flow of chemically active N 2 O 4 at high temperatures. The method has been used to study corrosive behaviour of chromium at temperatures 923, 1073 and 1273 K. The time of exposure amounts up to 140 hours. The wave-like time dependence of mass velocity variation has been observed for all chromium samples under test. The time of the alloy exposure to N 2 O 4 medium and the nature of the alloying affect this dependence. The given metallograhic studies of chromium alloys show complex structure of the surface layer

Mechanical-thermal synthesis of chromium carbides

International Nuclear Information System (INIS)

Cintho, Osvaldo Mitsuyuki; Favilla, Eliane Aparecida Peixoto; Capocchi, Jose Deodoro Trani

2007-01-01

The present investigation deals with the synthesis of chromium carbides (Cr 3 C 2 and Cr 7 C 3 ), starting from metallic chromium (obtained from the reduction of Cr 2 O 3 with Al) and carbon (graphite). The synthesis was carried out via high energy milling, followed by heat-treating of pellets made of different milled mixtures at 800 o C, for 2 h, under an atmosphere of argon. A SPEX CertPrep 8000 Mixer/Mill was used for milling under argon atmosphere. A tool steel vat and two 12.7 mm diameter chromium steel balls were used. The raw materials used and the products were characterized by differential thermal analysis, thermo gravimetric analysis, X-ray diffraction, electronic microscopy and X-ray fluorescence chemical analysis. The following variables were investigated: the quantity of carbon in the mixture, the milling time and the milling power. Mechanical activation of the reactant mixture depends upon the milling power ratio used for processing. The energy liberated by the reduction of the chromium oxide with aluminium exhibits a maximum for milling power ratio between 5:1 and 7.5:1. Self-propagating reaction occurred for all heat-treated samples whatever the carbon content of the sample and the milling power ratio used. Bearing carbon samples exhibited hollow shell structures after the reaction. The level of iron contamination of the milled samples was kept below 0.3% Fe. The self-propagated reaction caused high temperatures inside the samples as it may be seen by the occurrence of spherules, dendrites and whiskers. The carbon content determines the type of chromium carbide formed

Chloride Test

Science.gov (United States)

... metabolic acidosis ) or when a person hyperventilates (causing respiratory alkalosis ). A decreased level of blood chloride (called hypochloremia) ... disease , emphysema or other chronic lung diseases (causing respiratory ... metabolic alkalosis). An increased level of urine chloride can indicate ...

Contingency plans for chromium utilization. Publication NMAB-335

International Nuclear Information System (INIS)

1978-01-01

The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. This vulnerability results because chromium is essential for the fabrication of corrosion-resisting steels and high-temperature, oxidation-resisting alloys in applications that are vital to the nation's technological well-being; because no substitutes are known for these materials in those applications; and because the known, substantial deposits of chromite ore are only in a few geographical locations that could become inaccessible to the United States as a result of political actions. 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

Superfund Record of Decision (EPA Region 5): Midco II, Gary, IN. (First remedial action), (amendment), April 1992

International Nuclear Information System (INIS)

1992-01-01

The 7-acre Midco II site is an abandoned chemical waste storage and disposal facility in Gary, Indiana. Land use in the surrounding area is predominantly industrial. The underlying aquifer, which is used primarily for non-drinking purposes, is highly susceptible to contamination from surface sources. From 1976 to 1978, the site was used for treatment, storage, and disposal of chemical and bulk liquid wastes. The ROD amends a 1989 ROD that addressed the remaining contaminated soil, pit wastes, and ground water by treatment of an estimated 35,000 cubic yards of soil wastes. The amended remedy reduces the estimated amount of soil to be treated, as a result of new information on arsenic data and amended soil CALs, further defines the site cover requirements, and further defines the requirements for deep well injection of contaminated ground water. The primary contaminants of concern affecting the subsurface soil, sediment, and ground water are VOCs, including methylene chloride, benzene, toluene, TCE, and xylenes; other organics, including PCBs, phenols, and PAHs; and metals, including chromium, and lead. The amended remedial action for the ROD is included

Fluid balance and chloride load in the first 24h of ICU admission and its relation with renal replacement therapies through a multicentre, retrospective, case-control study paired by APACHE-II.

Science.gov (United States)

González-Castro, A; Ortiz-Lasa, M; Leizaola, O; Salgado, E; Irriguible, T; Sánchez-Satorra, M; Lomas-Fernández, C; Barral-Segade, P; Cordero-Vallejo, M; Rodrigo-Calabia, E; Dierssen-Sotos, T

2017-05-01

To analyse the association between water balance during the first 24h of admission to ICU and the variables related to chloride levels (chloride loading, type of fluid administered, hyperchloraemia), with the development of acute kidney injury renal replacement therapy (AKI-RRT) during patients' admission to ICU. Multicentre case-control study. Hospital-based, national, carried out in 6 ICUs. Cases were patients older than 18 years who developed an AKI-RRT. Controls were patients older than 18 years admitted to the same institutions during the study period, who did not develop AKI-RRT during ICU admission. Pairing was done by APACHE-II. An analysis of unconditional logistic regression adjusted for age, sex, APACHE-II and water balance (in evaluating the type of fluid). We analysed the variables of 430 patients: 215 cases and 215 controls. An increase of 10% of the possibility of developing AKI-RRT per 500ml of positive water balance was evident (OR: 1.09 [95% CI: 1.05 to 1.14]; P<.001). The study of mean values of chloride load administered did not show differences between the group of cases and controls (299.35±254.91 vs. 301.67±234.63; P=.92). The water balance in the first 24h of ICU admission relates to the development of IRA-TRR, regardless of chloraemia. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Effects of chromium on the immune system.

Science.gov (United States)

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. Copyright 2002 Federation of European Microbiological Societies

Bioavailability of a potato chromium complex to the laboratory rat

International Nuclear Information System (INIS)

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 μg 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

Assessment of the level of chromium species in the discharged ...

African Journals Online (AJOL)

The purpose of this study was to assess the level of chromium species in the discharged effluents of selected tanneries in the Amhara Region; Haik and Debre Berhan tanneries. The level of total chromium, and hexavalent chromium in the discharged effluent of the studied tanneries were determined using the ICP-OES, and ...

Spectrophotometric determination of chromium in geological samples

International Nuclear Information System (INIS)

Rathore, D.P.S.; Tarafder, P.K.

1992-01-01

A method for the determination of chromium is presented, based on the oxidation of hydroxylamine hydrochloride to nitrous acid by chromium(VI) in acetic acid medium followed by diazotization of the nitrite produced with p-aminophenylmercaptoacetic acid and subsequent coupling of the diazonium salt with N-(1-naphthyl)ethylenediamine di-hydrochloride in acidic medium to form a stable blueish azo dye. The method is suitable for the determination of chromium(VI) from 0.04 to 1.2 mg l -1 in a 1.0-cm cuvette. The molar absorptivity and Sandell's sensitivity are 3.65x10 4 l mol -1 cm -1 and 0.0014μg cm -2 , respectively. (author). 17 refs.; 3 figs

Chromium and aging

Science.gov (United States)

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...

Stabilization of carbon dioxide and chromium slag via carbonation.

Science.gov (United States)

Wu, Xingxing; Yu, Binbin; Xu, Wei; Fan, Zheng; Wu, Zucheng; Zhang, Huimin

2017-08-01

As the main greenhouse gas, CO 2 is considered as a threat in the context of global warming. Many available technologies to reduce CO 2 emission was about CO 2 separation from coal combustion and geological sequestration. However, how to deal with the cost-effective storage of CO 2 has become a new challenge. Moreover, chromium pollution, the treatment of which requires huge energy consumption, has attracted people's widespread attention. This study is aimed to develop the sequestration of CO 2 via chromium slag. A dynamic leaching experiment of chromium slag was designed to testify the ability of CO 2 adsorption onto chromium slag and to release Cr(VI) for stabilization. The results showed that the accumulative amounts of Cr(VI) were ca. 2.6 mg/g released from the chromium slag after 24 h of leaching. In addition, ca. 89 mg/g CO 2 was adsorbed by using pure CO 2 in the experiment at 12 h. Calcite is the only carbonate species in the post-carbonated slag analyzed by powder X-ray diffraction and thermal analysis. The approach provides the feasibility of the utilization of chromium slag and sequestration of the carbon dioxide at the same time at ordinary temperatures and pressures.

Removal of Chromium and Lead from Industrial Wastewater Using

Directory of Open Access Journals (Sweden)

Mohamed Hilal

2013-04-01

Full Text Available In this research an attempt is made on the ability of aerobic treatment of synthetic solutions containing lead and chromium using effective microorganisms within the reactor. To achieve the desired objectives of the research, synthetic aqueous solutions of lead and chromium was used in the concentration of chromium and lead ions of 5, 10,50 and 100 mg / l .The work was done at constant pH equal to 4.5 and temperature of 30 ± 1 º C. Effective microorganisms solutions was added to the reactor at Vol.% of 1/50 ,1/100 ,1/500 and 1/1000, with retention time was 24 hours to measure the heavy metals concentration the atomic absorption device was used. The experimental results showed that each 1mg / l of lead and chromium ions need 24 mg of effective microorganisms to achieve removal of 92.0% and 82.60% for lead and chromium respectively. Increasing the concentration of effective microorganisms increases the surface of adsorption and thus increasing the removal efficiency. It is found that the microorganisms activity occur in the first five hours of processing and about 94% of adsorption capacity of biomass will take place. It is also found the selectivity of microorganisms to lead ions is higher than for chromium ions.

Determination of chromium (VI) in primary and secondary fertilizer and their respective precursors.

Science.gov (United States)

Krüger, Oliver; Fiedler, Francesca; Adam, Christian; Vogel, Christian; Senz, Rainer

2017-09-01

Hexavalent chromium species (Cr(VI)) are often carcinogenic, of high acute toxicity, highly mobile, and thus pose a severe risk to health and environment. Fertilizers usually contain significant amounts of chromium. Therefore, a reliable analysis of chromium and the fraction of Cr(VI) are crucial for safe use of fertilizers. This problem is expected to increase in the future, since more and more recycled fertilizers emerge due to increasing fertilizer demand and respective supply risks. However, existing analytical methods have been developed for conventional fertilizers and have to be tested whether they are suitable for the new materials. Thus, we performed a wet-chemical extraction for Cr(VI) on several matrices as well as respective quality control experiments including spiking with Cr(III) and Cr(VI) compounds. We found the Cr(VI) amounts to be below 2 mg/kg except for a thermally post-treated sewage sludge ash (SSA) that showed 12.3 mg/kg. The presence of organic matter e.g. in sludge or precipitated struvite caused a reduction of spiked Cr(VI) and thus no satisfying recovery for quality control. Cr(VI) reduction was also observed for SSA, presumably due to the presence of Fe(II) compounds. Even though the tested procedure can be hampered in some recycled fertilizer matrices, it might be adapted to be applicable also for these complex samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption and desorption of hydrolyzed metal ions. 3. Scandium and chromium

International Nuclear Information System (INIS)

Gray, B.; Matijevic, E.; Clarkson Univ., Potsdam, NY

1987-01-01

Adsorption of scandium(III) and chromium(III) species on a PVC latex was measured using radioactive isotopes; the uptake increased with increasing pH. The data were interpreted by combining aspects of the models of James and Healy and also of Anderson and Bockris. The experimental and calculated results agree quite well for scandium, but not for chromium. The deviation in the latter case is believed to be due to polymerization of the hydrolyzed chromium cations and to the interaction of chromium with the anionic surface groups of the latex. Neither of these interactions occur with scandium. Hydrolyzed scandium species adsorbed on the latex were removed by acidifying the dispersion, while chromium complexes were not, substantiating the proposed difference in the chemical nature of chromium and scandium species at the solid/solution interface. 32 refs.; 8 figs.; 8 tabs

High temperature corrosion of nickel alloys by molten calcium chloride in an oxidising environment

International Nuclear Information System (INIS)

Barnett, Roger; Gittos, Mike

2012-09-01

A series of nickel alloys was submerged in molten calcium chloride (a molten salt proposed for and used in the nuclear industry for a variety of applications), at 850 deg. C for 72 hours under an oxidising environment. The samples were analysed in detail, in order to determine their corrosion behaviour and suitability for use under these conditions. 310 stainless steel was used as a reference material. Extensive corrosion occurred and the observed attack on the metal substrates was general and massive with corrosion rates ranging from 1.17 mm/year, for Haynes 214, to 13.3 mm/year, for 310 stainless steel. All materials showed selective leaching of chromium from the samples but the oxide layer formed was not protective, spalling away easily. The severity of the attack was not immediately visible from the corrosion rate alone: samples showed a friable scale on the surface and deep penetration of the attack beneath, up to 0.63 mm for 310 stainless steel. In some cases, the attack was clearly intergranular with chromium being depleted along the grain boundaries, whereas in others, the attack was more general. No simple correlation between alloying elements and corrosion rate was apparent, with additions of aluminium and silicon appearing to have little or no protective effect. Alloys 600 and Haynes HR-160 showed promise, with relatively low corrosion rates and penetration depths. (authors)

[Biological significance of chromium III for the human organism].

Science.gov (United States)

Piotrowska, Anna; Pilch, Wanda; Tota, Łukasz; Nowak, Gabriel

2018-03-09

Currently, chromium is probably the most controversial transition metal. In recent publications it is clearly stated that it is not an essential micronutrient and should be considered to have a pharmacological effect. Conflicting scientific reports along with a huge amount of dietary supplements, as well as dietary and sports nutrients available on the market have prompted the authors to investigate the available information on the range of possible application, efficacy and safety of products containing salts or chelates of chromium III. The authors reviewed articles in electronic databases for the years 1959-2016, and selected works describing the biochemical, physiological and toxic properties of chromium salts and chelates and the range of possible applications in medicine, dietetics and sport. A critical analysis of reports dealing with the effect of chromium on the carbohydrate and lipid metabolism, body composition, lean body mass and sports performance was carried out. The authors indicated papers analyzing the mechanism of action of chromium in the cognitive and affective disorders. Much attention has been paid to the safety use of chromium III supplements. There are still some unsolved issues. In the field of toxicology, a limited number of reports about environmental exposure to trivalent chromium in the workplace draws our attention. In the field of biochemical research, there is still a need to clarify the mechanism of psychiatric and endocrinological activity, especially in conjunction with the immune system. Med Pr 2018;69(2):211-223. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

76 FR 8773 - Superalloy Degassed Chromium From Japan

Science.gov (United States)

2011-02-15

... INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-1090 (Review)] Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission. ACTION: Termination of five-year... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to lead...

Molecular Mechanisms of Chromium in Alleviating Insulin Resistance

Science.gov (United States)

Hua, Yinan; Clark, Suzanne; Ren, Jun; Sreejayan, Nair

2011-01-01

Type 2 diabetes is often associated with obesity, dyslipidemia, and cardiovascular anomalies and is a major health problem approaching global epidemic proportions. Insulin resistance, a prediabetic condition, precedes the onset of frank type 2 diabetes and offers potential avenues for early intervention to treat the disease. Although lifestyle modifications and exercise can reduce the incidence of diabetes, compliance has proved to be difficult, warranting pharmacological interventions. However, most of the currently available drugs that improve insulin sensitivity have adverse effects. Therefore, attractive strategies to alleviate insulin resistance include dietary supplements. One such supplement is chromium, which has been shown reduce insulin resistance in some, but not all, studies. Furthermore, the molecular mechanisms of chromium in alleviating insulin resistance remain elusive. This review examines emerging reports on the effect of chromium, as well as molecular and cellular mechanisms by which chromium may provide beneficial effects in alleviating insulin resistance. PMID:22423897

Use of supplemental cementitious materials for optimum resistance of concrete to chloride penetration.

Science.gov (United States)

1989-01-01

This study was conducted to determine whether significant improvements could be achieved in the resistance to the penetration by chloride ions of concretes with fly ash or slag by the addition of silica fume with either Type II or Type III cement and...

Biosorption of hexavalent chromium in a tannery industry wastewater using fungi species

International Nuclear Information System (INIS)

Sivakumar, D.

2016-01-01

The isolated fungi species of different kinds from chromium contaminated soil sites located in Nagalkeni, Chennai were used for reducing chromium(VI) in a tannery industry wastewater of Nagalkeni, Chennai. The experiments were conducted to know biosorption potential of isolated fungi species for removing chromium(VI) in a tannery industry wastewater against the different p H, fungi biomass and chromium(VI) concentration (dilution ratio). The results of this study indicated that the order of maximum removal of chromium(VI) by an isolated fungi species at an optimum pH of 3, fungi biomass of 4g and an initial chromium(VI) concentration of 18.125 mg/L (dilution ratio 4) is A. niger > A. flavus > A. fumigatus > A. nidulans > A. heteromorphus > A. foetidus > A. viridinutans. This study found that the maximum removal of chromium(VI) was achieved by Aspergillus niger (96.3 %) than other fungi species at chromium(VI) concentration of 18.125 mg/L in a tannery industry wastewater. The chromium removal from tannery industry wastewater was validated by checking chromium removal in an aqueous solution and by checking the removal efficiency of other parameters in a tannery industry wastewater using same isolated A. niger. Biosorption model was proposed to simulate the experimental condition for removing chromium(VI) in a tannery industry wastewater by all isolated fungi species. The R2 and x2 values of the proposed model predicted that the proposed biosorption model is very much useful for predicting the trend of reduction potential of chromium(VI) in a tannery industry wastewater by all isolated fungi species. This study suggested that one could select the type of fungi species, ion concentration level, selection of treatment period, quantity of biomass to be used, and p H level of the medium, to achieve the highest reduction of any toxic metals from any contaminated water, wastewater and soil environment.

Adsorption of Chromium from Aqueous Solution Using Polyaniline

Directory of Open Access Journals (Sweden)

Majid Riahi Samani

2011-10-01

Full Text Available New group of polymers have been synthesized that are conductive of electricity so they are called conducting polymers. One of the most conducting polymers is "polyaniline". In the present study, polyaniline was synthesized by oxidizing aniline monomer under strongly acidic conditions using potassium iodate as an initiator of oxidative polymerization. Synthesized polyaniline as a powder used as an adsorbent to remove chromium from aqueous solution. Experiments were conducted in batch mode with variables such as amount of polyaniline, chromium solution pH and adsorbtion isotherms. Due to presence of Cr (III in solution after using polyaniline, removal mechanism is the combination of surface adsorption and reduction. It seems that polyaniline reduces the Cr(VI to Cr(III and adsorbs the Cr(III and a part of remaining  Cr(VI. It is well known that nitrogen atom in compounds of amine derivative makes co-ordinate bond with positive charge of metals due to the presence of electron in sp3 orbital of nitrogen. The majority of total chromium removal  occurred at 30minute for polyaniline  and the optimum  time for  hexavalent chromium  removal was about 5 min. Polyaniline has the maximum total cheomiume removal at pH, 3-9. The maximum hexavalent chromium removal occurred at acidic pH for polyanilines. The equilibrium adsorption data for polyaniline fitted both Freundlich’s and Langmuir’s isotherms. This research shows that polyaniline can be used as an adsorbent  for removal chromium from aqueous solution.

Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

NARCIS (Netherlands)

Weckhuysen, B.M.; Wachs, I.E.; Schoonheydt, R.A.

1996-01-01

Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

40 CFR 61.65 - Emission standard for ethylene dichloride, vinyl chloride and polyvinyl chloride plants.

Science.gov (United States)

2010-07-01

... dichloride, vinyl chloride and polyvinyl chloride plants. 61.65 Section 61.65 Protection of Environment... AIR POLLUTANTS National Emission Standard for Vinyl Chloride § 61.65 Emission standard for ethylene dichloride, vinyl chloride and polyvinyl chloride plants. An owner or operator of an ethylene dichloride...

Biosorption and biotransformation of chromium by Serratia sp. isolated from tannery effluent.

Science.gov (United States)

Srivastava, Shaili; Thakur, Indu Shekhar

2012-01-01

A bacterium isolated from soil and sediment ofa leather tanning mill's effluent was identified as Serratia sp. by the analysis of 16S rDNA. Scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) and transmission electron microscopy (TEM) were used to assess morphological changes and confirm chromium biosorption in Serratia sp. both in a shake-flask culture containing chromium and in a tannery wastewater. The SEMEDX and the elemental analysis of the chromate-containing samples confirmed the binding of chromium with the bacterial biomass. The TEM exhibited chromium accumulation throughout the bacterial cell, with some granular deposits in the cell periphery and in the cytoplasm. X-ray diffraction analysis (XRD) was used to quantify the chromium and to determine the chemical nature of the metal-microbe interaction. The XRD data showed the crystalline character of the precipitates, which consisted of mainly calcium chromium oxide, chromium fluoride phosphate and related organo-Cr(III) complex crystals. The XRD data also revealed a strong involvement of cellular carboxyl and phosphate groups in chromium binding by the bacterial biomass. The results of the study indicated that a combined mechanism of ion-exchange, complexation, croprecipitation and immobilization was involved in the biosorption of chromium by bacterial cells in contaminated environments.

Biosorption of chromium by mangrove-derived Aplanochytrium sp ...

African Journals Online (AJOL)

The microbial dried biomass of Thraustochytrids is used as bioadsorbent for the removal of the chromium in aqueous solution. In this investigation, three species of Thraustochydrids namely Aplanochytrium sp., Thraustochytrium sp. and Schizochytrium sp. were tested for the efficiency of chromium accumulation by culturing ...

Effects of UV light and chromium ions on wood flavonoids

International Nuclear Information System (INIS)

Molnárné Hamvas, L.; Németh, K.; Stipta, J.

2003-01-01

The individual and simultaneous effect of UV light and chromium ions was investigated by spectrophotometric methods on inert surfaces impregnated with quercetin or robinetin. The UV-VIS spectra of the silica gel plates impregnated with these flavonoids were modified characteristically after irradiating ultraviolet light. Even a half an hour of irradiation has caused irreversible changes in the molecule structure. A certain chemical - presumably complexation - was concluded from the change of spectral bands assigned to flavonoids when impregnated with chromic ions. Hexavalent chromium caused more complex changes in the absorption spectra. The differences in the spectra could indicate either the oxidation and decomposition of flavonoids, or some kind of coordination process and the reduction of hexavalent chromium. The simultaneous application of UV light and chromium ions caused more pronounced effects. The complexation process between chromium(III) and flavonoid was completed

Photocatalysis with chromium-doped TiO2: Bulk and surface doping

KAUST Repository

Ould-Chikh, Samy; Proux, Olivier; Afanasiev, Pavel V.; Khrouz, Lhoussain; Hedhili, Mohamed N.; Anjum, Dalaver H.; Harb, Moussab; Geantet, Christophe; Basset, Jean-Marie; Puzenat, Eric

2014-01-01

The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared

Synthesis and characterization of chromium doped boehmite nanofibres

International Nuclear Information System (INIS)

Yang Jing; Frost, Ray L.; Yuan Yong

2009-01-01

Thermogravimetric and differential thermogravimetric analysis has been used to study synthesised chromium doped boehmite. The dehydroxylation temperature increases significantly from 0 to 5% doping, after which the dehydroxylation temperature shows a small steady increase up to the 20% doping level. The temperature of dehydroxylation increases with time of hydrothermal treatment. Chromium doped boehmite nanofibres were also characterised by X-ray diffraction and transmission electron microscopy. Hydrothermal treatment of doped boehmite with chromium resulted in the formation of nanofibres over a wide dopant range. Nanofibres up to 500 nm in length and between 4 and 6 nm in width were produced

Role of Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 as Bioindicators and Immobilizers of Chromium in a Contaminated Natural Environment.

Science.gov (United States)

Millach, Laia; Solé, Antoni; Esteve, Isabel

2015-01-01

The aim of this work was to study the potential of the two phototrophic microorganisms, both isolated from Ebro Delta microbial mats, to be used as bioindicators and immobilizers of chromium. The results obtained indicated that (i) the Minimum Metal Concentration (MMC) significantly affecting Chlorophyll a intensity in Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 was 0.25 µM and 0.75 µM, respectively, these values being lower than those established by current legislation, and (ii) Scenedesmus sp. DE2009 was able to immobilize chromium externally in extracellular polymeric substances (EPS) and intracellularly in polyphosphate (PP) inclusions. Additionally, this microorganism maintained high viability, including at 500 µM. Based on these results, we postulate that Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 are good chromium-indicators of cytotoxicity and, further, that Scenedesmus sp. DE2009 plays an important role in immobilizing this metal in a contaminated natural environment.

Role of Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 as Bioindicators and Immobilizers of Chromium in a Contaminated Natural Environment

Directory of Open Access Journals (Sweden)

Laia Millach

2015-01-01

Full Text Available The aim of this work was to study the potential of the two phototrophic microorganisms, both isolated from Ebro Delta microbial mats, to be used as bioindicators and immobilizers of chromium. The results obtained indicated that (i the Minimum Metal Concentration (MMC significantly affecting Chlorophyll a intensity in Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 was 0.25 µM and 0.75 µM, respectively, these values being lower than those established by current legislation, and (ii Scenedesmus sp. DE2009 was able to immobilize chromium externally in extracellular polymeric substances (EPS and intracellularly in polyphosphate (PP inclusions. Additionally, this microorganism maintained high viability, including at 500 µM. Based on these results, we postulate that Geitlerinema sp. DE2011 and Scenedesmus sp. DE2009 are good chromium-indicators of cytotoxicity and, further, that Scenedesmus sp. DE2009 plays an important role in immobilizing this metal in a contaminated natural environment.

Chromium tolerance and reduction potential of Staphylococci ...

African Journals Online (AJOL)

In order to study the microbiology of chromium tolerance and reduction at a fly ash dumping site in South Africa, 15 core samples were investigated. It was shown that the 30 year old dumping site exhibited high concentrations of Cr (VI) ranging from 1.6 to 9.6 mg/g. From this contaminated fly ash dumping site, 67 chromium ...

Study of Physical modifications induced by chromium doping of uranium dioxide

International Nuclear Information System (INIS)

Fraczkiewicz, M.

2010-01-01

Improvement of nuclear fuel performances requires reducing fission gas release. Doping uranium dioxide with chromium is the improvement axis considered in this work. Indeed, chromium fastens crystal growth in UO 2 , and thus enables a significant increase of the grain size. This work aims at the identification of defects produced by chromium addition in UO 2 , and their impact on properties of interest of the material. First, defects existing in doped fuel directly after sintering have been studied. X-ray Absorption Spectroscopy allowed the identification of the environment of solubilised chromium in UO 2 . Chromium atoms are roughly substituting for uranium atoms, but generate a complete reorganisation of neighbouring oxygen atoms, and distortion of uranium sublattice. Characterisation of transport properties (electrical conductivity and oxygen self-diffusion) have shown that because of charge balance, chromium plays a leading role on such properties. A model of point defects in UO 2 has been proposed, showing how complex the involved phenomena are. Observations by Transmission Electron Microscopy of ion-irradiated thin foils have shown that chromium makes the coalescence of irradiation defects easier. This behaviour can be explained by a stabilisation of defect clusters due to precipitation of chromium. Finally, study of thermal diffusion of helium in doped UO 2 , performed by Nuclear Reaction Analysis, has confirmed this interaction between chromium atoms and irradiation defects. Indeed, μ-NRA measures have shown no fast gas diffusion close to grain boundaries, in contrast with standard UO 2 behaviour, which is associated with defects recovery in grain boundaries. (author) [fr

I. Cis-dichlorodiammineplatinum(II). Aquation equilibria and isotopic exchange of chloride ligands with free chloride and tetrachloroplatinate(II). II. The Szilard--Chalmers effect in solid-state systems containing the octa-μ3-chloro-octahedro-hexamolybdenum(II) cluster

International Nuclear Information System (INIS)

Lee, K.W.

1976-06-01

A titration technique was utilized to determine the equilibrium quotients for the first and second aquation steps of cis-Pt(NH 3 ) 2 Cl 2 . At 25.0 0 C and an ionic strength of 0.318 M the first and second aquation equilibrium constants are: K 1 = 3.63 +- 0.22 x 10 -3 M, ΔH 1 0 = 3.4 kcal and K 2 = 1.11 +- 0.14 x 10 -4 M, ΔH 2 0 = 10 kcal. In the ternary system, cis-Pt(NH 3 ) 2 Cl 2 :PtCl 4 2- :Cl - , the kinetics of isotopic exchange of chlorine was investigated. In addition to the expected route of exchange via aquation, a direct exchange of chlorine ligands between cis-Pt(NH 3 ) 2 Cl 2 and PtCl 4 2- occurred which is described by the rate expression. Separation procedures were devised for partial resolution of component yields resulting from dissolving a neutron-irradiated sample of (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O in 1.5 N HCl. A recrystallization procedure was formulated to determine the retention of activity in the parent compound of molybdenum(II) chloride clusters after neutron irradiation. The retention found in an aqueous 1.5 N HCl solution containing 1 percent (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O is 0.64 percent. For a solid sample of (H 3 O) 2 [(Mo 6 Cl 8 )Cl 6 ] . 6H 2 O aged 24 hours in Dry Ice after neutron irradiation, a retention of 7.0 percent was observed. Under the same conditions, a sample of (Mo 6 Cl 8 )Cl 4 with 0.8 percent and 2.7 percent water had retentions of 25.0 percent and 11.1 percent, respectively. Effects of thermal annealing and gamma ray treatment on solid samples of [(Mo 6 Cl 8 )Cl 4 ] . 2H 2 O were investigated

Electrochemical modification of chromium surfaces using 4-nitro- and4-fluorobenzenediazonium salts

DEFF Research Database (Denmark)

Hinge, Mogens; Cecatto, Marcel; Kingshott, Peter

2009-01-01

Chromium surfaces can be electrografted with organic surface films using 4-nitro- or 4-fluorobenzenediazonium salts, despite the fact that the surfaces are covered with a protective chromium oxide layer......Chromium surfaces can be electrografted with organic surface films using 4-nitro- or 4-fluorobenzenediazonium salts, despite the fact that the surfaces are covered with a protective chromium oxide layer...

Beidellite and other natural low-cost sorbents to remove chromium and cadmium from water and wastewater

Directory of Open Access Journals (Sweden)

Callejas, P.

2010-04-01

Full Text Available Laboratory experiments were conducted to examine ability of clay minerals and organic matter to remove the cadmium(II and chromium(III ions from aqueous effluents. Sample materials for the experiments were taken in Poland and Spain. Their chemical composition, specific surface area, pH in water and potassium chloride, ion exchange capacity and absorption of Cr (III and Cd (II have been studied. The clay samples exhibited greater sorption capacity for Cr(III than for Cd(II while organic matter, especially brown coal, better sorbed Cd(II than Cr(III. The Langmuir binding strength parameter (k was always greater for Cr than for Cd. On the basis of the sequential extraction and microanalysis by SEM it was stated that iron oxides were not involved in the Cd ion binding while their role in Cr(III binding was essential. Ion binding by Fe oxides and their missing at exchangeable positions yields weak both susceptibility to leaching and mobility of Cr(III ions. Instead, Cd(II ions are mainly bound at exchangeable positions, susceptible to leaching.

La industria y las urbes descargan sobre los ríos aguas que representan un factor importante en la contaminación medioambiental. La agricultura se ve afectada, siendo uno de los problemas el alto contenido en metales pesados presentes en el suelo o las aguas utilizadas para el riego. En este trabajo se expone la posibilidad de utilizar materiales de bajo costo, minerales arcillosos y carboníferos, tomados en España y Polonia, para remediar esta contaminación. Se ha estudiado su composición química, superficie específica, pH en agua y cloruro potásico, capacidad de intercambio iónica y absorción de Cr (III y Cd(II. Las muestras arcillosas mostraron mayor capacidad de absorción para el ion Cr(III que para el Cd(II, mientras que las orgánicas, especialmente la denominada “ brown coal” (lignito, fueron mejores adsorbentes del ion Cd. El parámetro k obtenido en las isotermas de absorci

Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers

Directory of Open Access Journals (Sweden)

Ren Xiao-Bin

2011-04-01

Full Text Available Abstract Background Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI exposure can cause DNA damage in electroplating workers. Methods 157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%. Urinary 8-OHdG levels were measured by ELISA. Results Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 μg/L than that in control subjects (1.54 μg/L, P P P P Conclusion The findings in this study indicated that there was detectable chromium exposure in electroplating workers. Low-level occupational chromium exposure induced DNA damage.

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

Science.gov (United States)

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 subject...

Influence of chloride and bromide anions on localized corrosion of 15%Cr ferritic stainless steel

International Nuclear Information System (INIS)

Lee, Seung Uk; Ahn, Jae Chen; Kim, Dong Hyun; Hong, Seung Chan; Lee, Kyung Sub

2006-01-01

The influence of Cl - (919 ppm) and a mixture of Cl - (919 ppm) and Br - (51 ppm) on the corrosion behavior of 15%Cr ferritic stainless steel was investigated. Potentiodynamic and immersion tests were performed to examine the corrosion behavior. The size and the shape of pits were observed by optical microscope and scanning electron microscope. The oxide films formed on stainless steel were investigated by X-ray photoelectron spectroscopy (XPS). During the immersion test at 93 deg. C for 600 h, Fe and Cr were mostly corroded to iron and chromium oxides. The results of depth profiling indicate higher corrosion rate of solution containing chloride than the mixture solution. It was clear that the addition of Br - to the solution containing Cl - inhibited the localized corrosion of 15%Cr ferritic stainless steel

Review of occupational epidemiology of chromium chemicals and respiratory cancer.

Science.gov (United States)

Hayes, R B

1988-06-01

Several epidemiologic studies have investigated the association between cancer risk and employment in chromium producing and using industries. Strong and consistent associations have been found between employment in the primary chemical producing industry and the risk for respiratory cancer. Workers employed in chromate pigment production and possibly spray painters of chromate pigment paints appear to be at excess risk of respiratory cancer. Chrome platers may also be at excess risk, although the evidence is limited. A few studies indicate that chromium alloy welding may also be an exposure source of concern. Some studies of ferrochromium alloy workers have shown an excess risk for respiratory cancer, although the risk may in part be due to concomitant exposures. The evidence indicates that the hexavalent form of chromium is the primary agent of chromium carcinogenesis. Solubility and other characteristics of chromium compounds may also play a role in determining risk.

Solubility of Copper(II Sulfate and Dicopper Chloride Trihydroxide for Pigs

Directory of Open Access Journals (Sweden)

C. S. Park

2016-11-01

Full Text Available This study was conducted to determine the solubility of copper (Cu in two sources of copper(II sulfate (CuSO4 including monohydrate and pentahydrate and three sources of dicopper chloride trihydroxide (dCCTH including α-form (dCCTH-α, β-form (dCCTH-β, and a mixture of α- and β-form (dCCTH-αβ at different pH and a 3-step in vitro digestion assay for pigs. In Exp. 1, Cu sources were incubated in water-based buffers at pH 2.0, 3.0, 4.8, and 6.8 for 4 h using a shaking incubator at 39°C. The CuSO4 sources were completely dissolved within 15 min except at pH 6.8. The solubility of Cu in dCCTH-α was greater (p<0.05 than dCCTH-β but was not different from dCCTH-αβ during 3-h incubation at pH 2.0 and during 2-h incubation at pH 3.0. At pH 4.8, there were no significant differences in solubility of Cu in dCCTH sources. Copper in dCCTH sources were non-soluble at pH 6.8. In Exp. 2, the solubility of Cu was determined during the 3-step in vitro digestion assay for pigs. All sources of Cu were completely dissolved in step 1 which simulated digestion in the stomach. In Exp. 3, the solubility of Cu in experimental diets including a control diet and diets containing 250 mg/kg of additional Cu from five Cu sources was determined during the in vitro digestion assay. The solubility of Cu in diets containing additional Cu sources were greater (p<0.05 than the control diet in step 1. In conclusion, the solubility of Cu was influenced by pH of digesta but was not different among sources based on the in vitro digestion assay.

Problems in the determination of chromium in biological materials

International Nuclear Information System (INIS)

Behne, D.; Braetter, P.; Gessner, H.; Hube, G.; Mertz, W.; Roesick, U.

1976-01-01

The effects of sample preparation on the analysis of chromium in biological matter have been investigated using brewer's yeast as a test material. The apparent chromium content of the yeast as determined by flameless atomic absorption spectrometry was significantly higher after destruction of the organic matter with HNO 3 in a closed pressure vessel than after wet-ashing in open vessels and after direct introduction of the sample into the graphite furnace. The results obtained by neutron activation analysis without any sample preparation, which corresponded to the atomic absorption values after digestion in the pressure vessel, showed that considerable errors arise in the other methods of sample treatment. Chromium analysis of dried and ashed yeast suggest that losses of volatile chromium compounds may occur during heating. (orig.) [de

Hexavalent Chromium IV-Free Primer Development

Science.gov (United States)

Alldredge, Michael J.; Buck, Amy L.

2015-01-01

Primer materials provide corrosion protection for metal parts as well as an increased adhesion between metallic substrates and thermal protection systems (TPSs). Current primers for use in cryogenic applications contain hexavalent chromium. This hexavalent chromium provides excellent corrosion protection even in a cryogenic environment, but it is a carcinogen that requires special equipment and waste control procedures to use. The hazardous nature of hexavalent chromium makes it an obsolescence risk in the future. This study included two phases of evaluation. Thirteen primers were initially identified as candidates and twelve of those primers were tested in phase 1. Four of the best performing candidates from phase 1 continued into phase 2 testing. Phase 1 testing consisted mostly of liquid constituent and physical property testing. Cryoflex and salt fog testing were included in phase 1 because of their importance to the overall success of a candidate material. Phase 2 consisted of physical, thermal, and mechanical properties for nominally processed and fabricated specimens.

Chloride flux in phagocytes.

Science.gov (United States)

Wang, Guoshun

2016-09-01

Phagocytes, such as neutrophils and macrophages, engulf microbes into phagosomes and launch chemical attacks to kill and degrade them. Such a critical innate immune function necessitates ion participation. Chloride, the most abundant anion in the human body, is an indispensable constituent of the myeloperoxidase (MPO)-H2 O2 -halide system that produces the potent microbicide hypochlorous acid (HOCl). It also serves as a balancing ion to set membrane potentials, optimize cytosolic and phagosomal pH, and regulate phagosomal enzymatic activities. Deficient supply of this anion to or defective attainment of this anion by phagocytes is linked to innate immune defects. However, how phagocytes acquire chloride from their residing environment especially when they are deployed to epithelium-lined lumens, and how chloride is intracellularly transported to phagosomes remain largely unknown. This review article will provide an overview of chloride protein carriers, potential mechanisms for phagocytic chloride preservation and acquisition, intracellular chloride supply to phagosomes for oxidant production, and methods to measure chloride levels in phagocytes and their phagosomes. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Integrated Criteria Document Chromium

NARCIS (Netherlands)

Slooff W; Cleven RFMJ; Janus JA; van der Poel P; van Beelen P; Boumans LJM; Canton JH; Eerens HC; Krajnc EI; de Leeuw FAAM; Matthijsen AJCM; van de Meent D; van der Meulen A; Mohn GR; Wijland GC; de Bruijn PJ; van Keulen A; Verburgh JJ; van der Woerd KF

1990-01-01

Betreft de engelse versie van rapport 758701001
Bij dit rapport behoort een appendix onder hetzelfde nummer getiteld: "Integrated Criteria Document Chromium: Effects" Auteurs: Janus JA; Krajnc EI
(appendix: see 710401002A)

A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

Directory of Open Access Journals (Sweden)

Inga Zinicovscaia

2012-12-01

Full Text Available Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The main source of chromium pollution including the Republic o Moldova is industry. It is a great need to develop new eco-friendly methods of chromium removal. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. This article is an extended abstract of a communication presented at the Conference Ecological Chemistry 2012

The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

International Nuclear Information System (INIS)

Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D.

2004-01-01

X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca 2 Ge 0.8 Cr 0.2 O 4 , Ba 2 Ge 0.1 Cr 0.9 O 4 , Sr 2 CrO 4 , Ca 2 (PO 4 ) x (CrO 4 ) 1-x Cl (x=0.25,0.5), Ca 5 (CrO 4 ) 3 Cl, CrO 3 , the octahedrally coordinated compounds Cr(II)-acetate, CrCl 3 , CrF 3 , Cr 2 O 3 , KCr(SO 4 ) 2 · 12H 2 O, CrO 2 and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code

The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

Science.gov (United States)

Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D.

2004-05-01

X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca 2Ge 0.8Cr 0.2O 4, Ba 2Ge 0.1Cr 0.9O 4, Sr 2CrO 4, Ca 2(PO 4) x(CrO 4) 1- xCl ( x=0.25,0.5), Ca 5(CrO 4) 3Cl, CrO 3, the octahedrally coordinated compounds Cr(II)-acetate, CrCl 3, CrF 3, Cr 2O 3, KCr(SO 4) 2 · 12H 2O, CrO 2 and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code.

Chromium related degradation of solid oxide fuel cells; Chrom-bezogene Degradation von Festoxid-Brennstoffzellen

Energy Technology Data Exchange (ETDEWEB)

Neumann, Anita

2011-05-04

Solid Oxide Fuel Cells (SOFCs) offer a high potential for application as an auxiliary power unit (APU) for heavy goods vehicles as well as combined heat and power (CHP) systems. SOFCs are especially attractive due to their high efficiencies and the use of different fuel types. However, optimization in terms of long term stability and costs are still necessary. This work characterized the degradation of SOFCs with lanthanum strontium manganite (LSM) cathodes under chromium influence. Galvanostatic cell tests were carried out at 800 C with operation times from 250 - 3000 h and variation of the chromium source and current density. The current densities of j = 0 (A)/(cm{sup 2}), j = 0,3 (A)/(cm{sup 2}) and j = 0,5 (A)/(cm{sup 2}) were applied. The high temperature ferritic alloy Crofer22APU was used as a chromium source. Variation of the chromium source was realized by coating the Crofer22APU insert with the chromium retention layer Mn{sub 3}O{sub 4} and the cathode contact layer LCC10. Cell degradation was analyzed with regard to cell voltage, current density and area specific resistance (ASR). Microstructural alterations of the cathode as well as chromium content and distribution across the cell were investigated after completion of the cell tests. For cells with a chromium source present and operation with a nonzero current density, the course of cell degradation was divided into three phases: a run-in, weak linear degradation and strong linear degradation. A decrease of the chromium release rate by means of different coatings stretched the course of degradation along the timescale. Strong degradation, which is characterized by a significant increase in ASR as well as a decrease of current density at the operating point, was only observed when a chromium source in the setup was comb ined with operation of the cell with a non-zero current density. Operation of the cell with a chromium source but no current density caused a degradation of current density at the

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

Science.gov (United States)

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...

Toxicity assessment and geochemical model of chromium leaching from AOD slag.

Science.gov (United States)

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Increase of chromium tolerance in Scenedesmus acutus after sulfur starvation: Chromium uptake and compartmentalization in two strains with different sensitivities to Cr(VI).

Science.gov (United States)

Marieschi, M; Gorbi, G; Zanni, C; Sardella, A; Torelli, A

2015-10-01

In photosynthetic organisms sulfate constitutes the main sulfur source for the biosynthesis of GSH and its precursor Cys. Hence, sulfur availability can modulate the capacity to cope with environmental stresses, a phenomenon known as SIR/SED (Sulfur Induced Resistance or Sulfur Enhanced Defence). Since chromate may compete for sulfate transport into the cells, in this study chromium accumulation and tolerance were investigated in relation to sulfur availability in two strains of the unicellular green alga Scenedesmus acutus with different Cr-sensitivities. Paradoxically, sulfur deprivation has been demonstrated to induce a transient increase of Cr-tolerance in both strains. Sulfur deprivation is known to enhance the sulfate uptake/assimilation pathway leading to important consequences on Cr-tolerance: (i) reduced chromate uptake due to the induction of high affinity sulfate transporters (ii) higher production of cysteine and GSH which can play a role both through the formation of unsoluble complexes and their sequestration in inert compartments. To investigate the role of the above mentioned mechanisms, Cr accumulation in total cells and in different cell compartments (cell wall, membranes, soluble and miscellaneous fractions) was analyzed in both sulfur-starved and unstarved cells. Both strains mainly accumulated chromium in the soluble fraction, but the uptake was higher in the wild-type. In this type a short period of sulfur starvation before Cr(VI) treatment lowered chromium accumulation to the level observed in the unstarved Cr-tolerant strain, in which Cr uptake seems instead less influenced by S-starvation, since no significant decrease was observed. The increase in Cr-tolerance following S-starvation seems thus to rely on different mechanisms in the two strains, suggesting the induction of a mechanism constitutively active in the Cr-tolerant strain, maybe a high affinity sulfate transporter also in the wild-type. Changes observed in the cell wall and

Effect of some addition agents on the electrodeposition of cadmium from acidic chloride baths

International Nuclear Information System (INIS)

Abd El-Halim, A.M.; Baghlaf, A.O.; Sobahi, M.I.

1984-01-01

A further development of a chloride-based cadmium plating bath containing 0.3 M CdCl 2 .(5/2)H 2 O, 0.1 M HCl, 0.4 M H 3 BO 3 and 2.0 M NH 4 Cl (bath I) is described. The influences of the individual addition agents thiourea, coumarin Ni 2+ ions and I - ions on the characteristics of cadmium electrodeposition from acidic chloride electrolytes containing 0.3 M CdCl 2 .(5/2)H 2 O, 0.1 M HCl, 0.4 M H 3 BO 3 , 2.0 M NH 4 Cl, 0.5 M sodium potassium tartrate and 5 g gelatin l -1 (bath II) were studied. Bath II including a combination of the four above-mentioned additives was denoted bath III. The additive-containing bath III produced a brighter but less hard cadmium deposit than the additive-free bath II. The individual effects of melamine, 3-methyl-4-p-methoxyphenylazopyrazol-5-one, dimethylformamide (DMF) and DMF with biacetyl-bis-(benzoylhydrazone) on the cathodic polarization and current efficiency of cadmium electrodeposition from baths II and III, as well as on the morphology and microhardness of the as-plated cadmium deposits, were investigated and discussed. (Auth.)

Influence of Chloride-Ion Adsorption Agent on Chloride Ions in Concrete and Mortar

Directory of Open Access Journals (Sweden)

Gai-Fei Peng

2014-04-01

Full Text Available The influence of a chloride-ion adsorption agent (Cl agent in short, composed of zeolite, calcium aluminate hydrate and calcium nitrite, on the ingress of chloride ions into concrete and mortar has been experimentally studied. The permeability of concrete was measured, and the chloride ion content in mortar was tested. The experimental results reveal that the Cl agent could adsorb chloride ions effectively, which had penetrated into concrete and mortar. When the Cl agent was used at a dosage of 6% by mass of cementitious materials in mortar, the resistance to the penetration of chloride ions could be improved greatly, which was more pronounced when a combination of the Cl agent and fly ash or slag was employed. Such an effect is not the result of the low permeability of the mortar, but might be a result of the interaction between the Cl agent and the chloride ions penetrated into the mortar. There are two possible mechanisms for the interaction between the Cl agent and chloride ion ingress. One is the reaction between calcium aluminate hydrate in the Cl agent and chloride ions to form Friedel’s salt, and the other one is that calcium aluminate hydrate reacts with calcium nitrite to form AFm during the early-age hydration of mortar and later the NO2− in AFm is replaced by chloride ions, which then penetrate into the mortar, also forming Friedel’s salt. More research is needed to confirm the mechanisms.

Plasma Spraying and Characterization of Chromium Carbide-Nickel Chromium Coatings

Czech Academy of Sciences Publication Activity Database

Ctibor, Pavel; Prantnerová, M.

2016-01-01

Roč. 9, č. 4 (2016), s. 281-290, č. článku PCCC-2016-09-16-339. ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Chromium carbide * Slurry abrasion * Dry rubber wheel test * Friction * Microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass http://www.pccc.icrc.ac.ir/?xid=0113010121000001804&id=976

Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

Energy Technology Data Exchange (ETDEWEB)

Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander [Institute of Physics, Faculty of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, Piastów 48, 70-311 Szczecin (Poland); Adamski, Paweł; Moszyński, Dariusz [Institute of Inorganic Chemical Technology and Environment Engineering, West Pomeranian University of Technology, Szczecin, Pułaskiego 10, 70-322 Szczecin (Poland)

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.

CHROMIUM BIOACCUMULATION FROM COMPOSTS AND VERMICOMPOSTS BASED ON TANNERY SLUDGES

Directory of Open Access Journals (Sweden)

Krzysztof GONDEK

2008-07-01

Full Text Available Storage of waste substances is not indifferent to ecological equilibrium in the environment therefore should not be the ultimate way to limit waste arduousness. Therefore, the conducted investigations aimed to determine the effect of tannery composts and vermicomposts loaded with chromium on this element bioaccumulation in earthworm bodies and biomass of selected plants. Chromium in composts and vermicomposts based on tannery sludges occurred in small quantities and easily soluble compounds. Chromium concentrations in redworm biomass points to this metal accumulation in Eisenia fetida body tissues. This element content in redworm biomass was signifi cantly positively correlated with its content in composts. Chromium content in plants was diversifi ed and on treatments was generally smaller than on mineral treatment or farmyard manure. Chromium absorbed by plants was stored mainly in the root systems, and over the norm content of this element found in vermicomposts did not cause its excessive accumulation in plant biomass.

Recovery of Cd(II), Co(II) and Ni(II) from Chloride Medium by Solvent Extraction Using CYANEX 923 and CYANEX 272 I

International Nuclear Information System (INIS)

Ahmed, M.; El Dessouky, S.I.; El-Nadi, Y.A.; Daoud, J.A.; Saad, E.A.

2008-01-01

The paper aims to study the extraction and separation of Cd(II), Co(II) and Ni(II) from their mixtures in hydrochloric acid medium with CYANEX 923 in kerosene. Preliminary investigations showed that only Cd(II) is extracted with CYANEX 923 while Co(II) and Ni(II) are not extracted. Different parameters affecting the extraction of Cd(II) with CYANEX 923 such as hydrochloric acid, hydrogen ion, extractant and metal concentrations, temperature investigations were also investigated. The stoichiometry of the extracted metal species investigated was found to be HCdCl 3 . 2 CYANEX 923. The stripping of the extracted Cd(II) species is obtained with 0.1 M HCl solution. Co(II) was found to be extracted with CYANEX 272 at ph 5.8 leaving Ni(II) in the solution. A developed process for the sequential of Cd(II), Co(II) and Ni(II) from their mixture in hydrochloric acid medium is proposed

Luminescence properties of copper(I), zinc(II) and cadmium(II) coordination compounds with picoline ligands

Energy Technology Data Exchange (ETDEWEB)

Małecki, Jan Grzegorz, E-mail: gmalecki@us.edu.pl; Maroń, Anna

2017-06-15

Mononuclear coordination compounds of copper(I) – [Cu(PPh{sub 3}){sub 2}(picoline)(NO{sub 3})], zinc(II) – [ZnCl{sub 2}(picoline){sub 2}] (picoline=3– and 4–methylpyridine) and polymeric cadmium(II) – [CdCl{sub 2}(β-picoline){sub 2}]{sub n} were prepared and their luminescence properties in solid state and acetonitrile solutions were determined. Single crystal X-ray crystallography revealed distorted tetrahedral geometry around the central ions of the compounds. The compounds exhibit green photoluminescence in solid state and in acetonitrile solutions. The emission of copper(I) compounds originated from metal-to-ligand charge transfer state combined with nitrato-to-picoline charge transfer state i.e. ({sup 1}(M+X)LCT). The presence of nitrato ligand in the coordination sphere of copper(I) compounds quenches the emission. Luminescence of zinc(II) and cadmium(II) compounds results from chloride-to-picoline charge transfer state and the quantum efficiency in the case of the polymeric Cd(II) compound reaches 39%. The photoluminescence quantum yields of the mononuclear zinc(II) compounds vary from 10 to 16% depending on the conditions (solid state, solution). - Graphical abstract: Coordination compounds of copper(I), zinc(II) and polymeric cadmium(II) with picoline ligands were prepared and their luminescence properties in solid state and acetonitrile solutions were determined. The compounds exhibit green photoluminescence in solid state and in acetonitrile solutions. Emission of copper(I) compounds originated from {sup 1}(M+X)LCT state. Luminescence of zinc(II) and cadmium(II) compounds results from chloride-to-picoline charge transfer state and the quantum efficiency in the case of the polymeric Cd(II) compound reaches 39%. The photoluminescence quantum yields of the mononuclear zinc(II) compounds vary from 10 to 16% depending on the conditions (solid state, solution).

Bioremediation of chromium in tannery effluent by microbial consortia

African Journals Online (AJOL)

USER

2010-05-24

May 24, 2010 ... Chromium is the most toxic and common among the heavy metal pollutants of industrial effluents .... Chromium (Cleseari and Green, 1995) included the oxidation of .... like uranium in its cells might also match with its tendency.

Bone marrow scintigraphy using 111Indium chloride in patients with aplastic anemia

International Nuclear Information System (INIS)

Mabuchi, Nobuhisa; Kumano, Machiko; Matsumoto, Fumiko; Arita, Shigehiro; Nakagawa, Kenichi; Fujii, Koichi; Yoshioka, Hiroyasu; Hamada, Tatsumi; Ishida, Osamu

1987-01-01

Bone marrow scintigraphy using 111 Indium chloride ( 111 In-chloride) was performed in 18 patients with aplastic anemia. The scintigrams were taken 48 hours after an intravenous injection of 111 In-chloride 3 mCi. The distribution patterns on scintigram were classified into 5 types: Type I (4 cases) showed no accumulation, Type II (6 cases) showed low accumulation in usual bone marrow sites. Type III (7 cases) showed island-like distribution in bone marrow sites. Type IV, although no case was included in the 18 patients, shows uneven distribution between pelvis and sternum or vertebrae. Type V (one case) showed almost normal accumulation in usual bone marrow sites. Bone marrow uptake of 111 In-chloride correlated well with the cellularity of bone marrow. There was a tendency for the cases of markedly increased saturated iron-binding capacity to show increased renal activity. In type III, both the percentage of cases who had been treated and the count of reticulocytes were higher than those in the other types, which suggested that island-like distribution on scintigram showed the regeneration responded to the therapy, and related to the erythropoietic function. (author)

The solvent extraction of zinc, iron, and indium from chloride solutions by neutral organophosphorus compounds

International Nuclear Information System (INIS)

Preston, J.S.; Du Preez, A.C.

1985-01-01

The preparation of several neutral organophosphorus compounds and their evaluation as selective extractants for zinc in chloride media are described. The compounds belong to the series trialkyl phosphates (RO) 3 PO, dialkyl alkylphosphonates R'PO(OR) 2 , alkyl dialkylphosphinates R 2 'PO(OR), and trialkyl-phosphine oxides R 3 'PO. They were characterized by measurement of their physical properties (melting and boiling points, refractive indices, and densities), and their purities were confirmed by osmometric determination of their molecular masses; by carbon and hydrogen microanalysis; by the titrimetric determination of acidic impurities; and, for liquid products, by comparison of their experimental molar refractivities with empirical values. Metal-distribution equilibria were determined for solutions of the extractants in xylene and aqueous phase containing 0,5 to 5,0 M sodium chloride. Moderately good selectivities were shown for zinc(II) over iron(III), and excellent selectivities were shown for zinc(II) over iron(II), copper(II), lead(II), and cadmium(II). The extraction of indium(III) was similar to that of zinc(II). The extraction of zinc(III), iron(III), and indium(III) increased markedly through the series. (RO) 3 PO 2 2 'PO(OR) 3 'PO. The incorporation of phenyl groups into the compounds led to weaker extraction. The extracted complexes of zinc(II), iron(III), and indium(III) have the stoichiometries ZnCl 2 L 2 ,FeCl 3 L 2 (H 2 O), and InCl 3 L 2 (H 2 O) respectively, where L represents the neutral organophosphorus compound

Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Panda, L. [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India); Das, B., E-mail: bdas@immt.res.in [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India); Rao, D.S.; Mishra, B.K. [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India)

2011-08-30

Graphical abstract: Dolochar - a waste material from sponge iron industry, is put to test as an adsorbent for removal of cadmium and hexavalent chromium ions from aqueous solutions. The sample consists of lots of voids and pores. Batch adsorption experiments have indicated that, higher pH and temperature enhances sorption for cadmium ions. The adsorption for chromium is found better at acidic pH in comparison to alkaline pH. The adsorption is well fitted to Langmuir isotherm model compared to the Freundlich model indicating monolayer adsorption. The kinetics of adsorption better fit to pseudo second order model.. Display Omitted Highlights: {yields} Dolochar, a waste material is generated during the production of sponge iron. {yields} Dolochar consists of metallic iron, carbon, and lime bearing phases along with lots of voids and pores. {yields} It was found to be an good adsorbent for the removal of cadmium and hexavalent chromium ions from aqueous solutions. {yields} The adsorption follows Langmuir isotherm and kinetics of adsorption better fit of pseudo second order model. - Abstract: Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6 m{sup 2}/g and micropore area of 34.1 m{sup 2}/g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast

Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions

International Nuclear Information System (INIS)

Panda, L.; Das, B.; Rao, D.S.; Mishra, B.K.

2011-01-01

Graphical abstract: Dolochar - a waste material from sponge iron industry, is put to test as an adsorbent for removal of cadmium and hexavalent chromium ions from aqueous solutions. The sample consists of lots of voids and pores. Batch adsorption experiments have indicated that, higher pH and temperature enhances sorption for cadmium ions. The adsorption for chromium is found better at acidic pH in comparison to alkaline pH. The adsorption is well fitted to Langmuir isotherm model compared to the Freundlich model indicating monolayer adsorption. The kinetics of adsorption better fit to pseudo second order model.. Display Omitted Highlights: → Dolochar, a waste material is generated during the production of sponge iron. → Dolochar consists of metallic iron, carbon, and lime bearing phases along with lots of voids and pores. → It was found to be an good adsorbent for the removal of cadmium and hexavalent chromium ions from aqueous solutions. → The adsorption follows Langmuir isotherm and kinetics of adsorption better fit of pseudo second order model. - Abstract: Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6 m 2 /g and micropore area of 34.1 m 2 /g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast, the adsorption for Cr

Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

Science.gov (United States)

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

2016-09-01

Four nanocomposites containing mixed phases of Co3Mo3N and Co2Mo3N doped with chromium have been prepared. A linear fit is found for relation between Co2Mo3N 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.

Industrial Implementation of Environmentally Friendly Nanometal Electroplating Process for Chromium and Copper Beryllium Replacement using Low Cost Pulse Current Power Supplies

Science.gov (United States)

2014-09-10

FINAL REPORT Industrial Implementation of Environmentally Friendly Nanometal Electroplating Process for Chromium and Copper Beryllium...35 3.2 Phase II – Development/Verification that Nanotechnology Based Electroplating Process to Replace EHC/Cu-Be Processes are Compatible With...36 3.3 Phase III – Development of 200kW Power Supply and Compatible Nanostructured Electroplating Processed for Commercialization

Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers.

Science.gov (United States)

Zhang, Xu-Hui; Zhang, Xuan; Wang, Xu-Chu; Jin, Li-Fen; Yang, Zhang-Ping; Jiang, Cai-Xia; Chen, Qing; Ren, Xiao-Bin; Cao, Jian-Zhong; Wang, Qiang; Zhu, Yi-Min

2011-04-12

Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI)) exposure can cause DNA damage in electroplating workers. 157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%). Urinary 8-OHdG levels were measured by ELISA. Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 μg/L) than that in control subjects (1.54 μg/L, P electroplating workers. Low-level occupational chromium exposure induced DNA damage.

Wet skins tanning with chromium in dense CO2 under pressure

International Nuclear Information System (INIS)

Saldinari, L.; Dutel, Ch.; Perre, Ch.

2000-01-01

An ancestral gesture steadily improved through the centuries, the transformation of skins into leather includes several stages of which the principal one is tanning. Today, 90 % of the world's leather products are tanned with chromium. However, this stage is an environmental liability, and reducing the volume and chromium content of the waste has become a major issue. A first study on skin degreasing by dense CO 2 helped sharply reduce the volume of the fatty effluents. To replace water by dense CO 2 as the tanning medium was the logical next step. The present study was carried out in cooperation with three tanneries in the Rhone-Alpes-Auvergne area of France and a manufacturer of tanning materials. The difficulty of the study was the chemically opposed character of the two media involved. CO 2 is a non-polar and lipophilic solvent while inorganic chromium is insoluble. The water present in the treated skin is a polar and ionic reaction medium and one of the reagents in tanning chemistry. The mixture of these two partially miscible compounds gives a pH 3 by carbonic acid formation. Tanning is based on the reactivity of collagen, the main component of the skin, with hydroxylated complexes of chromium. Collagen is a protein containing some chemical functions, amines (R-NH 2 ) and carboxylic (R-COOH) for example. These functions impart an amphoteric character to the compound. The WERNER theory of complex salts explains the formation of hydroxylated complexes of chromium and their fixing on the carboxylic functions of collagen by oxolation. pH is the key parameter in tanning. The success of the process demands chromium impregnation without fixing it at a pH lower than 5, and then to fix it by increasing the pH. This opened two alternatives for transferring chromium in the skin: solubilize chromium in CO 2 via soluble organometallic complexes; or put the chromium salt into suspension without solubilizing it. The best results were obtained with the second option, which

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

Science.gov (United States)

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 to...

Light-induced reduction of rhodium(III) and palladium(II) on titanium dioxide dispersions and the selective photochemical separation and recovery of gold(III), platinum(IV), and rhodium(III) in chloride media

Energy Technology Data Exchange (ETDEWEB)

Borgarello, E.; Serpone, N.; Emo, G.; Harris, R.; Pelizzetti, E.; Minero, C.

1986-12-03

Irradiation of aqueous TiO/sub 2/ dispersions containing palladium(II) or rhodium(III) chloride salts with AM1 simulated sunlight leads to the photoreduction of these metals, which are deposited on the semiconductor particle surface. Oxygen is detrimental to the photoreduction of rhodium(III) but not the photoreduction of palladium(II). However, in both cases the reduction process is most efficient if the solution contains CH/sub 3/OH, which acts to scavenge valence band holes of the illuminated TiO/sub 2/ semiconductor. The selective photoreduction and recovery of precious metals from a dilute solution (as might be found in industrial wastes) have been investigated for a mixture of gold(III), platinum(IV), and rhodium(III) chloride salts as a function of various parameters (pH, presence or absence of O/sub 2/, presence or absence of a hole scavenger, and the concentration of the semiconductor). At pH 0, gold is easily separated from platinum and rhodium. The rate of photoreduction of gold(III) on TiO/sub 2/ is nearly independent of the concentration of the semiconductor, under the experimental conditions employed; the limiting rate is 2.7 x 10/sup -7/ M s/sup -1/. The potential utility of this selective photochemical technique is discussed.

Chromium Waste Treatment from Leather Manufacture Using Electron Beam Radiation Technic

International Nuclear Information System (INIS)

Didiek Herhady, R.; Sukarsono, R.

2007-01-01

Leather manufacture chromium waste treatment using chemical methods have an essential disadvantage, because of the production of the secondary contamination of wastes and separated sediments used by reagents. Therefore, a new technique is needed to solve this problem. The aim of the research to learn the advantages of electron beam radiation for chromium waste treatment. Water radiolysis can be produced by the interaction between electron beam and water or liquid substances. This phenomenon produces many reducing agents and ions that could reduce chromium concentrations in the liquid waste. Ethyl alcohol as a scavenger was added in the waste samples, then the pH of varied from 1, 4, 8 to 12, then were irradiated. Irradiation were done by Electron Beam Machine with dose 15, 25, and 35 kGy. After irradiation, chromium concentration in the samples were analyzed by AAS and UV-vis spectrophotometer. The results had shown that chromium could be reduced by high dose electron beam. The optimum reduction of chromium was achieved at liquid waste pH 8 and irradiation dose 35 kGy. (author)

Radiation stability of chromium low alloys

International Nuclear Information System (INIS)

Chakin, V.P.; Kazakov, V.A.

1990-01-01

Radiation effect on the behaviour of mechanical properties and structure of chromium low alloys such as VKh-2K, KhP-3, VKhM in the wide range of temperatures and neutron fluences is studied. Radiation stability of the alloys is shown to be limited by low-temperature radiation embrittlement (LTRE), caused by radiation hardening as a result of formation of radiation-induced defects such as dislocation loops and vacancy voids in the structure. The methods for prevention LTRE of chromium alloys are suggested. 8 refs.; 8 figs

Liquid-liquid extraction of ion-association complexes of cobalt(II-4-(2-pyridylazoresorcinol with ditetrazolium salts

Directory of Open Access Journals (Sweden)

Divarova Vidka V.

2015-01-01

Full Text Available The formation and liquid-liquid extraction of ion-association complexes between Co(II-4-(2-Pyridylazoresorcinol (PAR anionic chelates and cations of three ditetrazolium chlorides were studied: Blue Tetrazolium chloride (BTC, Neotetrazolium chloride (NTC and Nitro Blue Tetrazolium chloride (NBT. The optimum conditions for the formation and solvent extraction of the ion-association comlpex chelates were determined. It has been found that in the systems of Co(II-PAR-DTS, the reactants are reacted in molar ratios 1:2:1 and the general formula of complexes was suggested. The extraction equilibria were investigated and quantitatively characterized by the equilibrium constants and the recovery factors. The analytical characteristics of the complexes were calculated.

Chloride test - blood

Science.gov (United States)

Serum chloride test ... A greater-than-normal level of chloride is called hyperchloremia. It may be due to: Carbonic anhydrase inhibitors (used to treat glaucoma) Diarrhea Metabolic acidosis Respiratory alkalosis (compensated) Renal ...

Chloride in diet

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/002417.htm Chloride in diet To use the sharing features on this page, please enable JavaScript. Chloride is found in many chemicals and other substances ...

Mercuric chloride poisoning

Science.gov (United States)

... page: //medlineplus.gov/ency/article/002474.htm Mercuric chloride poisoning To use the sharing features on this page, please enable JavaScript. Mercuric chloride is a very poisonous form of mercury. It ...

Improvement on simultaneous determination of chromium species in aqueous solution by ion chromatography and chemiluminescence detection

DEFF Research Database (Denmark)

Gammelgaard, Bente; Liao, Y.P.; Jons, O.

1997-01-01

A sensitive method for the simultaneous determination of chromium(III) and chromium(VI) was chromatography and chemiluminescence detection. Two Dionex ion-exchange guard columns in series, CG5 and AG7, were used to separate chromium(III) from chromium(VI). Chromium(VI) was reduced by potassium......, the stabilities of reductant and luminol solutions were studied. The linear range of the calibration curve for chromium(III) and chromium(VI) was 1-400 mu g l(-1). The detection limit was 0.12 mu g l(-1) for chromium(III) and 0.09 mu g l(-1) for chromium(VI), respectively. The precision at the 20 mu g l(-1) level...... was 1.4% for chromium(III) and 2.5% for chromium(VI), respectively. The accuracy of the chromium(III) determination was determined by analysis of the NIST standard reference material 1643c, Trace elements in water with the result 19.1 +/- 1.0 mu g Cr(III) l(-1) (certified value 19.0 +/- 0.6 mu g Cr...

Study to establish cost predictions for the production of Redox chemicals

Science.gov (United States)

Ammann, P. R.; Loreth, M.; Harvey, W. W.

1982-01-01

The chromium and iron chloride chemicals are significant first costs for NASA Redox energy storage systems. This study was performed to determine the lowest cost at which chromium and iron chlorides could be obtained for a complex of redox energy storage systems. In addition, since the solutions gradually become intermixed during the course of operation of Redox units, it was an objective to evaluate schemes for regeneration of the operating solutions. Three processes were evaluated for the production of chromium and iron chlorides. As a basis for the preliminary plant design and economic evaluation, it was assumed that the plant would produce about 25,000 tons of contained chromium as CrCl3 and an equivalent molar quantity of FeCl2. Preliminary plant designs, including materials and energy balances and sizing of major equipment, were prepared, and capital and operating costs were estimated.

Environmental exposure to arsenic and chromium in an industrial area

OpenAIRE

Vimercati, Luigi; Gatti, Maria F; Gagliardi, Tommaso; Cuccaro, Francesco; De Maria, Luigi; Caputi, Antonio; Quarato, Marco; Baldassarre, Antonio

2017-01-01

Arsenic and chromium are widespread environmental contaminants that affect global health due to their toxicity and carcinogenicity. To date, few studies have investigated exposure to arsenic and chromium in a population residing in a high-risk environmental area. The aim of this study is to evaluate the exposure to arsenic and chromium in the general population with no occupational exposure to these metals, resident in the industrial area of Taranto, Southern Italy, through biological monitor...

Sonochemical synthesis of cooper II sulfide nanoparticles and their use as radiolytic stabilizer in polyvinyl chloride matrix

International Nuclear Information System (INIS)

Freitas, Danubia Maria da Silva; Lima, Thaysa Araujo de; Aquino, Katia Aparecida da Silva; Araujo, Elmo S.

2013-01-01

Cooper (II) sulfide (CuS) was synthesized by sonochemical method. CuS crystals with hexagonal structure exhibit irregular aggregates of particles with an average size in the range of 250-900 nm. Commercial Polyvinyl chloride (PVC) containing CuS nanoparticles (PVC/CuS) at concentrations of 0.10; 0.30; 0.50 and 0.70 wt% were investigated. The samples were irradiated with gamma radiation ( 60 Co) at room temperature and air atmosphere. The viscosity-average molar mass (M v ) was measured for PVC systems without nanoparticles and with nanoparticles. Decrease in viscosity molar mass was observed when the systems were gamma irradiated reflect the random scission effects that take place in the main chain. Degradation index (DI) value was also obtained by viscosity analysis. DI results showed that the addition of CuS nanoparticles at 0.5 wt% into PVC matrix decreased the number of main chain scissions at dose of 25 kGy and was calculated a protection of 84% in PVC matrix. CuS nanoparticles act as free radical scavenger into gamma-irradiated PVC systems. The interactions between CuS and PVC favor action of nanoparticles as a good plasticizer in the PVC molecule. (author)

Method for electrodeposition of nickel--chromium alloys and coating of uranium

International Nuclear Information System (INIS)

Stromatt, R.W.; Lundquist, J.R.

1975-01-01

High-quality electrodeposits of nickel-chromium binary alloys in which the percentage of chromium is controlled can be obtained by the addition of a complexing agent such as ethylenediaminetetraacetic disodium salt to the plating solution. The nickel-chromium alloys were found to provide an excellent hydrogen barrier for the protection of uranium fuel elements. (U.S.)

Chloride removal from vitrification offgas

Energy Technology Data Exchange (ETDEWEB)

Slaathaug, E.J. [Westinghouse Hanford Co., Richland, WA (United States)

1995-06-01

This study identified and investigated techniques of selectively purging chlorides from the low-level waste (LLW) vitrification process with the purge stream acceptable for burial on the Hanford Site. Chlorides will be present in high concentration in several individual feeds to the LLW Vitrification Plant. The chlorides are highly volatile in combustion type melters and are readily absorbed by wet scrubbing of the melter offgas. The Tank Waste Remediation System (TWRS) process flow sheets show that the resulting chloride rich scrub solution is recycled back to the melter. The chlorides must be purged from the recycle loop to prevent the buildup of excessively high chloride concentrations.

Chloride removal from vitrification offgas

International Nuclear Information System (INIS)

Slaathaug, E.J.

1995-01-01

This study identified and investigated techniques of selectively purging chlorides from the low-level waste (LLW) vitrification process with the purge stream acceptable for burial on the Hanford Site. Chlorides will be present in high concentration in several individual feeds to the LLW Vitrification Plant. The chlorides are highly volatile in combustion type melters and are readily absorbed by wet scrubbing of the melter offgas. The Tank Waste Remediation System (TWRS) process flow sheets show that the resulting chloride rich scrub solution is recycled back to the melter. The chlorides must be purged from the recycle loop to prevent the buildup of excessively high chloride concentrations

In vitro Solubility of Copper(II) Sulfate and Dicopper Chloride Trihydroxide for Pigs.

Science.gov (United States)

Park, C S; Kim, B G

2016-11-01

This study was conducted to determine the solubility of copper (Cu) in two sources of copper(II) sulfate (CuSO 4 ) including monohydrate and pentahydrate and three sources of dicopper chloride trihydroxide (dCCTH) including α-form (dCCTH-α), β-form (dCCTH-β), and a mixture of α- and β-form (dCCTH-αβ) at different pH and a 3-step in vitro digestion assay for pigs. In Exp. 1, Cu sources were incubated in water-based buffers at pH 2.0, 3.0, 4.8, and 6.8 for 4 h using a shaking incubator at 39°C. The CuSO 4 sources were completely dissolved within 15 min except at pH 6.8. The solubility of Cu in dCCTH-α was greater (pCopper in dCCTH sources were non-soluble at pH 6.8. In Exp. 2, the solubility of Cu was determined during the 3-step in vitro digestion assay for pigs. All sources of Cu were completely dissolved in step 1 which simulated digestion in the stomach. In Exp. 3, the solubility of Cu in experimental diets including a control diet and diets containing 250 mg/kg of additional Cu from five Cu sources was determined during the in vitro digestion assay. The solubility of Cu in diets containing additional Cu sources were greater (p<0.05) than the control diet in step 1. In conclusion, the solubility of Cu was influenced by pH of digesta but was not different among sources based on the in vitro digestion assay.

Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

Science.gov (United States)

Volland, Stefanie; Lütz, Cornelius; Michalke, Bernhard; Lütz-Meindl, Ursula

2012-01-01

Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 μM Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron–oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased

Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

Energy Technology Data Exchange (ETDEWEB)

Volland, Stefanie, E-mail: Stefanie.Volland@stud.sbg.ac.at [Plant Physiology Division, Cell Biology Department, University of Salzburg, Hellbrunnerstr 34, 5020 Salzburg (Austria); Luetz, Cornelius, E-mail: cornelius.luetz@uibk.ac.at [Institute of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck (Austria); Michalke, Bernhard, E-mail: bernhard.michalke@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen, German Research Centre for Environmental Health, Institute of Ecological Chemistry, Ingolstaedter Landstrasse 1, 85764 Neuherberg (Germany); Luetz-Meindl, Ursula, E-mail: ursula.luetz-meindl@sbg.ac.at [Plant Physiology Division, Cell Biology Department, University of Salzburg, Hellbrunnerstr 34, 5020 Salzburg (Austria)

2012-03-15

Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 {mu}M Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron-oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased

Intracellular chromium localization and cell physiological response in the unicellular alga Micrasterias

International Nuclear Information System (INIS)

Volland, Stefanie; Lütz, Cornelius; Michalke, Bernhard; Lütz-Meindl, Ursula

2012-01-01

Various contaminants like metals and heavy metals are constantly released into the environment by anthropogenic activities. The heavy metal chromium has a wide industrial use and exists in two stable oxidation states: trivalent and hexavalent. Chromium can cause harm to cell metabolism and development, when it is taken up by plants instead of necessary micronutrients such as for example iron. The uptake of Cr VI into plant cells has been reported to be an active process via carriers of essential anions, while the cation Cr III seems to be taken up inactively. Micrasterias denticulata, an unicellular green alga of the family Desmidiaceae is a well-studied cell biological model organism. Cr III and VI had inhibiting effects on its cell development, while cell division rates were only impaired by Cr VI. Transmission electron microscopy (TEM) revealed ultrastructural changes such as increased vacuolization, condensed cytoplasm and dark precipitations in the cell wall after 3 weeks of Cr VI treatment. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) were applied to measure intracellular chromium distribution. Chromium was only detected after 3 weeks of 10 μM Cr VI treatment in electron dense precipitations found in bag-like structures along the inner side of the cell walls together with iron and elevated levels of oxygen, pointing toward an accumulation respectively extrusion of chromium in form of an iron–oxygen compound. Atomic emission spectroscopy (EMS) revealed that Micrasterias cells are able to accumulate considerable amounts of chromium and iron. During chromium treatment the Cr:Fe ratio shifted in favor of chromium, which implied that chromium may be taken up instead of iron. Significant and rapid increase of ROS production within the first 5 min of treatment confirms an active Cr VI uptake. SOD and CAT activity after Cr VI treatment did not show a response, while the glutathione pool determined by immuno-TEM decreased

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

Science.gov (United States)

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. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

2011-11-21

... 0750-AH39 Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium... the use of materials containing hexavalent chromium. DATES: Comment Date: Comments on the proposed... human health and environmental risks related to the use of hexavalent chromium. Hexavalent chromium is a...

Bis[2-(2-aminoethyl-1H-benzimidazole-κ2N2,N3](nitrato-κ2O,O′cobalt(II chloride trihydrate

Directory of Open Access Journals (Sweden)

Jing Zhao

2012-06-01

Full Text Available In the title compound, [Co(NO3(C9H11N32]Cl·3H2O, the CoII atom is coordinated by four N atoms from two chelating 2-(2-aminoethyl-1H-benzimidazole ligands and two O atoms from one nitrate anion in a distorted octahedral coordination environment. In the crystal, N—H...Cl, N—H...O, O—H...Cl and O—H...O hydrogen bonds link the complex cations, chloride anions and solvent water molecules into a three-dimensional network. π–π interactions between the imidazole and benzene rings and between the benzene rings are observed [centroid–centroid distances = 3.903 (3, 3.720 (3, 3.774 (3 and 3.926 (3 Å].

Determination of total chromium in tanned leather samples used in car industry.

Science.gov (United States)

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.

Information profiles on potential occupational hazards: Inorganic chromium compounds. Draft report (Second)

Energy Technology Data Exchange (ETDEWEB)

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.

Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds.

Science.gov (United States)

Dartsch, P C; Hildenbrand, S; Kimmel, R; Schmahl, F W

1998-09-01

In contrast to trivalent chromium (Cr(III)) compounds, hexavalent chromium ((Cr(VI)) compounds are oxidizing agents capable of directly inducing tissue damage and possessing carcinogenic, mutagenic and teratogenic potency. After oral or dermal absorption of Cr(VI), the kidney is the main target organ for chromium accumulation, which might result in acute tubular necrosis in humans. In contrast, an acute toxic effect of Cr(VI) on the liver has not yet been described. Therefore, we used two established epithelial cell lines from the kidney (Opossum kidney cells) and the liver (Hep G2 cells) to design an in vitro-assay which is able to examine acute toxic effects of chromium compounds. Cells of both cell lines were treated with various concentrations of Cr(III) and Cr(VI) ranging from 0.01 micromol/l to 1 mmol/l for 24 h. Thereafter, cell morphology, organization of the intracellular cytoskeleton, number of viable cells and mean cell volume were examined. The results show that Cr(VI), but not Cr(III), has an acute cytotoxic effect and causes a dose-dependent loss in cell viability. The effective dose that caused 50% of cell death was 5 micromol/l for kidney epithelial cells and 50 micromol/l for liver epithelial cells. This means that kidney epithelial cells are 10 times more sensitive towards Cr(VI) treatment than liver epithelial cells and this might explain the known nephrotoxicity in vivo. The loss in cell viability was accompanied by a rounding and detachment of the cells and a marked reduction of intracellular F-actin-containing stress fibers. Microtubules and intermediate-sized filaments were observed to be unaffected. Only in the case of kidney epithelial cells, a dose-dependent cell volume increase was observed after Cr(VI) treatment at concentrations up to 50 micromol/l. At higher concentrations, the cell volume decreased due to the high number of cells undergoing lysis and the appearance of cellular fragments. Various chloride channel blockers with

Reduction of chromium (VI by the indirect action of Thiobacillus thioparus

Directory of Open Access Journals (Sweden)

E. Donati

2003-03-01

Full Text Available The microbial reduction of chromium(VI to chromium(III has been one of the most widely studied forms of metal bioremediation. Recently, we have found that Thiobacillus ferrooxidans and Thiobacillus thiooxidans, growing on elemental sulphur, can indirectly promote chromium(VI reduction by producing reducing agents such as sulphite and thiosulphate, which abiotically reduce chromium(VI. Those species of Thiobacillus are acidophilic bacteria which grow optimally at pH values lower than 4. However, most of those reducing agents are stabilised at higher pH values. Thus, the present paper reports on the ability to reduce chromium(VI using another specie of Thiobacilli, Thiobacillus thioparus, which is able to grow at pH close to 7.0. T. thioparus cultures were carried out in a fermentation vessel containing medium and sulphur as the sole energy source and maintained at 30ºC and 400 rpm. The pH was adjusted to 6.0, 7.0 or 8.0 and maintained with the automatic addition of KOH. Our results show high chromium (VI reduction values (close to 100% at the end of bacterial growth at the three pH values. The results of these experiments are very promising for development of a microbiological process to be used in the detoxification of chromium(VI-polluted effluents.

Amine and Titanium (IV Chloride, Boron (III Chloride or Zirconium (IV Chloride-Promoted Baylis-Hillman Reactions

Directory of Open Access Journals (Sweden)

Shi-Cong Cui

2001-10-01

Full Text Available The Baylis-Hillman reactions of various aryl aldehydes with methyl vinyl ketone at temperatures below -20oC using Lewis acids such as titanium (IV chloride, boron (III chloride or zirconium (IV chloride in the presence of a catalytic amount of selected amines used as a Lewis bases afford the chlorinated compounds 1 as the major product in very high yields. Acrylonitrile can also undergo the same reaction to give the corresponding chlorinated product in moderate yield. A plausible reaction mechanism is proposed. However, if the reaction was carried out at room temperature (ca. 20oC, then the Z-configuration of the elimination product 3, derived from 1, was formed as the major product.

Chromium Enrichment on P11 Ferritic Steel by Pack Cementation

OpenAIRE

Fauzi F. A.; Kurniawan T.; Salwani M. S.; Bin Y. S.; Harun W. S. W.

2016-01-01

The future thermal power plant is expected to operate at higher temperature to improve its efficiency and to reduce greenhouse gas emission. This target requires better corrosion properties of ferritic steels, which commonly used as materials for superheater and reheater of boiler tubes. In this work, chromium enrichment on the surface of ferritic steel is studied. The deposited chromium is expected to become a reservoir for the formation of chromia protective layer. Chromium was deposited on...

Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

International Nuclear Information System (INIS)

Al-Zand, T.K.

1986-01-01

The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

Bioremediation of chromium in tannery effluent by microbial consortia

African Journals Online (AJOL)

Chromium is the most toxic and common among the heavy metal pollutants of industrial effluents. In the present work the chromium remediation ability of Bacillus subtilis, Pseudomonas aeruginosa and Saccharomyces cerevisiae in consortia and in their immobilized forms was studied and their efficiencies were compared.

The removal of chromium from wastewaters by activated bentonite

International Nuclear Information System (INIS)

Mellah, A.; Chegrouche, S.; Ait Ghezala, H.; Douar, L.

1994-12-01

The adsorption of chromium onto activated bentonite has been investigated. Adsorption isotherms were analysed to obtain the Langmuir and freundlich constants. The operating parameters (i.e pH, contact time, solid/liquid ratio, temperatureand initial chromium concentration) influenced the rate of adsorption have been studied

Electrothermal Vaporization-QQQ-ICP-MS for Determination of Chromium in Mainstream Cigarette Smoke Particulate.

Science.gov (United States)

Fresquez, Mark R; Gonzalez-Jimenez, Nathalie; Gray, Naudia; Valentin-Blasini, Liza; Watson, Clifford H; Pappas, R Steven

2017-05-01

Chromium is transported in mainstream tobacco smoke at very low concentrations. However, when chromium is deposited too deeply in the lungs for mucociliary clearance, or is in a particle that is too large to pass directly through tissues, it bioaccumulates in the lungs of smokers. It is important to determine the concentrations of chromium that are transported in mainstream smoke. Several reliable studies have resulted in reports of chromium concentrations in smoke particulate that were below limits of detection (LODs) for the instruments and methods employed. In this study, electrothermal vaporization-triple quad-inductively coupled plasma-mass spectrometry (ETV-QQQ-ICP-MS) was chosen for determination of chromium concentrations in mainstream smoke because of the high sensitivity of ETV combined with QQQ-ICP-MS. The smoke from five reference, quality control, and commercial cigarettes was analyzed using ETV-QQQ-ICP-MS with isotope dilution for quantitative determination of chromium. The method LOD was sufficiently low that chromium concentrations in mainstream smoke could indeed be determined. The chromium concentrations in the smoke particulate were between 0.60 and 1.03 ng/cigarette. The range of chromium concentrations was at or below previously reported LODs. Determination of the oxidation state of the chromium transported in mainstream smoke would also be important, in consideration of the fact that both chromium(III) and chromium(VI) oxidation states cause inhalation toxicity, but chromium(VI) is also a carcinogen. It was possible to separate the oxidation states using ETV-QQQ-ICP-MS. However, determination of individual species at the levels found in mainstream smoke particulate matter was not possible with the present method. Published by Oxford University Press 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Review article. Adverse hematological effects of hexavalent chromium: an overview

Directory of Open Access Journals (Sweden)

Ray Rina Rani

2016-06-01

Full Text Available Workers of tanneries, welding industries, factories manufacturing chromate containing paints are exposed to hexavalent chromium that increas¬es the risk of developing serious adverse health effects. This review elucidates the mode of action of hexavalent chromium on blood and its adverse effects. Both leukocyte and erythrocyte counts of blood sharply decreased in Swiss mice after two weeks of intraperitoneal treatment with Cr (VI, with the erythrocytes transforming into echinocytes. The hexavalent chromium in the blood is readily reduced to trivalent form and the reductive capacity of erythrocytes is much greater than that of plasma. Excess Cr (VI, not reduced in plasma, may enter erythrocytes and lymphocytes and in rodents it induces microcytic anemia. The toxic effects of chromium (VI include mitochondrial injury and DNA damage of blood cells that leads to carcinogenicity. Excess Cr (VI increases cytosolic Ca2+ activity and ATP depletion thereby inducing eryptosis. Se, vitamin C, and quercetin are assumed to have some protective effect against hexavalent chromium induced hematological disorders.

Chloride Transport in Heterogeneous Formation

Science.gov (United States)

Mukherjee, A.; Holt, R. M.

2017-12-01

The chloride mass balance (CMB) is a commonly-used method for estimating groundwater recharge. Observations of the vertical distribution of pore-water chloride are related to the groundwater infiltration rates (i.e. recharge rates). In CMB method, the chloride distribution is attributed mainly to the assumption of one dimensional piston flow. In many places, however, the vertical distribution of chloride will be influenced by heterogeneity, leading to horizontal movement of infiltrating waters. The impact of heterogeneity will be particularly important when recharge is locally focused. When recharge is focused in an area, horizontal movement of chloride-bearing waters, coupled with upward movement driven by evapotranspiration, may lead to chloride bulges that could be misinterpreted if the CMB method is used to estimate recharge. We numerically simulate chloride transport and evaluate the validity of the CMB method in highly heterogeneous systems. This simulation is conducted for the unsaturated zone of Ogallala, Antlers, and Gatuna (OAG) formations in Andrews County, Texas. A two dimensional finite element model will show the movement of chloride through heterogeneous systems. We expect to see chloride bulges not only close to the surface but also at depths characterized by horizontal or upward movement. A comparative study of focused recharge estimates in this study with available recharge data will be presented.

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

Science.gov (United States)

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

Energy Technology Data Exchange (ETDEWEB)

Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D

2004-05-10

X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca{sub 2}Ge{sub 0.8}Cr{sub 0.2}O{sub 4}, Ba{sub 2}Ge{sub 0.1}Cr{sub 0.9}O{sub 4}, Sr{sub 2}CrO{sub 4}, Ca{sub 2}(PO{sub 4}){sub x}(CrO{sub 4}){sub 1-x}Cl (x=0.25,0.5), Ca{sub 5}(CrO{sub 4}){sub 3}Cl, CrO{sub 3}, the octahedrally coordinated compounds Cr(II)-acetate, CrCl{sub 3}, CrF{sub 3}, Cr{sub 2}O{sub 3}, KCr(SO{sub 4}){sub 2} {center_dot} 12H{sub 2}O, CrO{sub 2} and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code.

Growth inhibition and effect on photosystem by three imidazolium chloride ionic liquids in rice seedlings

Energy Technology Data Exchange (ETDEWEB)

Liu, Huijun, E-mail: lhj@mail.zjgsu.edu.cn [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang Province (China); Zhang, Shuxian [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang Province (China); Jiaxing University, Jiaxing 314001, Zhejiang Province (China); Zhang, Xiaoqiang; Chen, Caidong [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, Zhejiang Province (China)

2015-04-09

Highlights: • The three ILs have phytotoxic on rice growth. • The antioxidant enzyme activities increased first and then declined with ILs concentration increased. • The Hill reaction activity decreased and the PS II of leaves was damaged by ILs. • The toxicity of ILs increased as the alkyl chain length increased as the order: [OMIM]Cl < [DMIM]Cl < [C{sub 12}MIM]Cl. - Abstract: The effects of three imidazolium chloride ionic liquids (ILs) including 1-octyl-3-methylimidazolium chloride ionic liquid ([OMIM]Cl), 1-decyl-3-methylimidazolium chloride ionic liquid ([DMIM]Cl) and 1-dodecyl-3-methylimidazolium chloride ionic liquid ([C{sub 12}MIM]Cl) were studied in hydroponically grown rice seedlings. The growth inhibition rate increased and the Hill reaction activity of isolated rice chloroplasts decreased with increasing ILs concentrations. The IC{sub 50,5d} for stem length was 0.70 mg/L of [OMIM]Cl, 0.15 mg/L of [DMIM]Cl, and 0.055 mg/L of [C{sub 12}MIM]Cl, respectively. The SOD, POD and CAT activities of chloroplast exhibited initial increases followed by decreases in activity with increasing ILs concentrations. Chlorophyll fluorescence parameters such as the maximum effective quantum yield of PSII(F{sub v}/F{sub m}), the potential activity of PSII(F{sub v}/F{sub 0}), the yield of photochemical quantum [Y(II)], the photochemical quenching coefficient (qP), the non-photochemical quenching coefficient (NPQ) and the relative electron transport ratio (rETR) were affected, showing that ILs will damage the PSII. The results demonstrated that imidazolium chloride ILs are phytotoxic to rice growth and their photosystem, the toxicity increased as the alkyl chain length increased with the following order: [OMIM]Cl < [DMIM]Cl < [C{sub 12}MIM]Cl. The results will help to better understand the possible role of the defense mechanism in rice caused by ILs exposure.

Electrochemical Chloride extraction using external electrodes?

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Pedersen, Anne Juul

2006-01-01

Electrochemical methods for the removal of chloride from concrete have been developed and the methods are primarily designed for situations where corrosion has started due to an increased chloride concentration in the vicinity of the reinforcement. In these methods the reinforcement is used...... as the cathode. However, some unwanted side effects can occur, including alkali-silica reaction and in some cases hydrogen embrittlement. It is also suggested also to use electrochemical chloride extraction in a preventive way in constructions where chloride induced corrosion is likely to be a problem after...... a period of time, i.e. remove the chlorides before the chloride front reaches the reinforcement. If the chlorides are removed from outer few centimetres from the surface, the chloride will not reach the reinforcement and cause damage. By using the electrochemical chloride removal in this preventive way...

Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium

International Nuclear Information System (INIS)

Yatirajam, V.; Arya, S.P.

1975-01-01

A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1 to 2 N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2 to 5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium. (author)

X-Ray Fluorescence Determination of the Surface Density of Chromium Nanolayers

Science.gov (United States)

Mashin, N. I.; Chernjaeva, E. A.; Tumanova, A. N.; Ershov, A. A.

2014-01-01

An auxiliary system consisting of thin-film layers of chromium deposited on a polymer film substrate is used to construct calibration curves for the relative intensities of the K α lines of chromium on bulk substrates of different elements as functions of the chromium surface density in the reference samples. Correction coefficients are calculated to take into account the absorption of primary radiation from an x-ray tube and analytical lines of the constituent elements of the substrate. A method is developed for determining the surface density of thin films of chromium when test and calibration samples are deposited on substrates of different materials.

Extended followup of a cohort of chromium production workers

Science.gov (United States)

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

Composite Coatings of Chromium and Nanodiamond Particles on Steel

Directory of Open Access Journals (Sweden)

Gidikova N.

2017-12-01

Full Text Available Chrome plating is used to improve the properties of metal surfaces like hardness, corrosion resistance and wear resistance in machine building. To further improve these properties, an electrodeposited chromium coating on steel, modified with nanodiamond particles is proposed. The nanodiamond particles (average size 4 nm measured by TEM are produced by detonation synthesis (NDDS. The composite coating (Cr+NDDS has an increased thickness, about two times greater microhardness and finer micro-structure compared to that of unmodified chromium coating obtained under the same galvanization conditions. In the microstructure of specimen obtained from chrome electrolyte with concentration of NDDS 25 g/l or more, “minisections” with chromium shell were found. They were identified by metallographic microscope and X-ray analyser on etched section of chromium plated sample. The object of further research is the dependence of the presence of NDDS in the composite coating from the nanodiamond particles concentration in the chroming electrolyte.

Influence of IR-laser irradiation on α-SiC-chromium silicides ceramics

International Nuclear Information System (INIS)

Vlasova, M.; Marquez Aguilar, P.A.; Resendiz-Gonzalez, M.C.; Kakazey, M.; Bykov, A.; Gonzalez Morales, I.

2005-01-01

This project investigated the influence of IR-laser irradiation (λ = 1064 nm, P = 240 mW) on composite ceramics SiC-chromium silicides (CrSi 2 , CrSi, Cr 5 Si 3 ) by methods of X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. Samples were irradiated in air. It was established that a surface temperature of 1990 K was required to melt chromium silicides, evaporate silicon from SiC, oxidize chromium silicides, and enrich superficial layer by carbon and chromium oxide

FP corrosion dependence on carbon and chromium content in Fe-Cr steel

International Nuclear Information System (INIS)

Sasaki, Koei; Tanigaki, Takanori; Fukumoto, Ken-ichi; Uno, Masayoshi

2015-01-01

In an attempt to investigate Cs or Cs-Te corrosion dependence on chromium or carbon content in Fe-Cr steel, cesium and Cs-Te corrosion test were performed to three specimens, Fe-9Cr-0C, Fe-9Cr-0.14C and Fe-13Cr-0.14C, for 100 hours at 973K in simulated high burn-up fuel pin environment. Cesium corrosion depth has no dependence on chromium or carbon content in Fe-Cr steel. Cs-Te corrosion was appeared in only Fe-13Cr-0.14C which has chromium carbides ranged along grain boundary. Appearance of the Cs-Te corrosion was determined by distribution or arrangement of chromium carbides which depends on chromium and carbon content. (author)

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

CERN Document Server

American Society for Testing and Materials. Philadelphia

2011-01-01

Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

Crystal structure, thermal and fluorescence properties of 2,2′:6′,2′′-terpyridine-1,1′,1′′-triium tetrachloridonickelate(II chloride

Directory of Open Access Journals (Sweden)

Ouahida Zeghouan

2017-12-01

Full Text Available The title compound, (C15H14N3[NiCl4]Cl, comprises an NiII cation tetrahedrally coordinated by four chloride anions, a non-coordinating chloride anion and an essentially planar terpyridinium trication (tpyH33+, in which the central pyridinium ring forms dihedral angles of 5.7 (2 and 6.0 (2° with the peripheral pyridinium rings. Three inter-species N—H...Cl hydrogen bonds are formed with the Cl− anion, which also forms a link between the (tpyH33+ cations through an aromatic C—H...Cl interaction, forming a zigzag chain extending along the 21 (b screw axis. Two of the anionic Cl atoms of the [NiCl4]2− anions form Ni—Cl...π interactions with separate pyridinium rings [Ni...Cg = 3.669 (3 and 3.916 (4 Å]. In the crystal, successive undulating inorganic and organic layers are formed, extending across the (100 plane. Thermogravimetric and differential thermal analysis (TGA/DTA indicate that the compound starts to decompose at 313 K and may be a candidate for use as a blue-light luminescent material.

Kinetic study on adsorption of Cr(VI), Ni(II), Cd(II) and Pb(II) ions from aqueous solutions using activated carbon prepared from Cucumis melo peel

Science.gov (United States)

Manjuladevi, M.; Anitha, R.; Manonmani, S.

2018-03-01

The adsorption of Cr(VI), Ni(II), Cd(II) and Pb(II), ions from aqueous solutions by Cucumis melo peel-activated carbon was investigated under laboratory conditions to assess its potential in removing metal ions. The adsorption behavior of metal ions onto CMAC was analyzed with Elovich, intra-particle diffusion rate equations and pseudo-first-order model. The rate constant of Elovich and intra-particle diffusion on CMAC increased in the sequence of Cr(VI) > Ni(II) > Cd(II) > Pb(II). According to the regression coefficients, it was observed that the kinetic adsorption data can fit better by the pseudo-first-order model compared to the second-order Lagergren's model with R 2 > 0.957. The maximum adsorption of metal ions onto the CMAC was found to be 97.95% for Chromium(VI), 98.78% for Ni(II), 98.55% for Pb(II) and 97.96% for Cd(II) at CMAC dose of 250 mg. The adsorption capacities followed the sequence Ni(II) ≈ Pb(II) > Cr(VI) ≈ Cd(II) and Ni(II) > Pb(II) > Cd(II) > Cr(VI). The optimum adsorption conditions selected were adsorbent dosage of 250 mg, pH of 3.0 for Cr(VI) and 6.0 for Ni(II), Cd(II) and Pb(II), adsorption concentration of 250 mg/L and contact time of 180.

Factors influencing chloride deposition in a coastal hilly area and application to chloride deposition mapping

Directory of Open Access Journals (Sweden)

H. Guan

2010-05-01

Full Text Available Chloride is commonly used as an environmental tracer for studying water flow and solute transport in the environment. It is especially useful for estimating groundwater recharge based on the commonly used chloride mass balance (CMB method. Strong spatial variability in chloride deposition in coastal areas is one difficulty encountered in appropriately applying the method. A high-resolution bulk chloride deposition map in the coastal region is thus needed. The aim of this study is to construct a chloride deposition map in the Mount Lofty Ranges (MLR, a coastal hilly area of approximately 9000 km² spatial extent in South Australia. We examined geographic (related to coastal distance, orographic, and atmospheric factors that may influence chloride deposition, using partial correlation and regression analyses. The results indicate that coastal distance, elevation, as well as terrain aspect and slope, appear to be significant factors controlling chloride deposition in the study area. Coastal distance accounts for 70% of spatial variability in bulk chloride deposition, with elevation, terrain aspect and slope an additional 15%. The results are incorporated into a de-trended residual kriging model (ASOADeK to produce a 1 km×1 km resolution bulk chloride deposition and concentration maps. The average uncertainty of the deposition map is about 20–30% in the western MLR, and 40–50% in the eastern MLR. The maps will form a useful basis for examining catchment chloride balance for the CMB application in the study area.

Biomonitoring chromium III or VI soluble pollution by moss chlorophyll fluorescence.

Science.gov (United States)

Chen, Yang-Er; Mao, Hao-Tian; Ma, Jie; Wu, Nan; Zhang, Chao-Ming; Su, Yan-Qiu; Zhang, Zhong-Wei; Yuan, Ming; Zhang, Huai-Yu; Zeng, Xian-Yin; Yuan, Shu

2018-03-01

We systematically compared the impacts of four Cr salts (chromic chloride, chromic nitrate, potassium chromate and potassium bichromate) on physiological parameters and chlorophyll fluorescence in indigenous moss Taxiphyllum taxirameum. Among the four Cr salts, K 2 Cr 2 O 7 treatment resulted in the most significant decrease in photosynthetic efficiency and antioxidant enzymes, increase in reactive oxygen species (ROS), and obvious cell death. Different form the higher plants, although hexavalent Cr(VI) salt treatments resulted in higher accumulation levels of Cr and were more toxic than Cr(III) salts, Cr(III) also induced significant changes in moss physiological parameters and chlorophyll fluorescence. Our results showed that Cr(III) and Cr(VI) could be monitored distinguishably according to the non-photochemical quenching (NPQ) fluorescence of sporadic purple and sporadic lavender images respectively. Then, the valence states and concentrations of Cr contaminations could be evaluated according to the image of maximum efficiency of PSII photochemistry (Fv/Fm) and the quantum yield of PSII electron transport (ΦPSII). Therefore, this study provides new ideas of moss's sensibility to Cr(III) and a new method to monitor Chromium contaminations rapidly and non-invasively in water. Copyright © 2017 Elsevier Ltd. All rights reserved.

The {sup 99m}Tc generator using poly zirconium chloride (PZC)

Energy Technology Data Exchange (ETDEWEB)

Wan Awang, Wan Anuar; Dahalan, Rehir; Kasim, Shaaban [Medical Technology Div., Malaysian Inst. for Nuclear Technology Research (MINT), Selangor (Malaysia)

1998-10-01

The {sup 99m}Tc generator system has been prepared using poly zirconium chloride (PZC) to replace alumina (Al{sub 2}O{sub 3}) as a adsorbent. The Mo-98 (MoO{sub 3}) was irradiated using our 1 MW TRIGA MARK II research reactor. The amount of Mo-99 adsorbed to the PZC has been studied and the yield from the elution was about 20%. (author)

Preparates for the production of technetium 99m radiodiagnostics

International Nuclear Information System (INIS)

Schmidt-Dunker, M.; Greb, W.

1984-01-01

The preparates serve the production of Tc 99m radiodiagnostics for the scintiscanning of bones or calcareous tumors, muscle tissue or arterial sclerosis. They consist of mixtures of a carboxy phosphonic acid and/or carboxy phosphonate or its water-soluble salts, as well as 1-5 wt.% of a Sn(II), Fe(II) or Cr(II) salt. The mixture has a pH value of 3 to 9. The preparates are in particular of phosphons-ethane-1,2-dicarbonic acid (mixture of di/trisodium slat of 2:1) and SnCl2; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and chromium (II) chloride; 2-phosphons-butane-1,2,4-tricarbonic acid (trisodium salt) and iron(II) sulphate; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and Sn(II) chloride; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and 2-phosphono-butane-1,2,4-tricarbonic acid (trisodium salt) and Fe(II) sulphate; or phosphons-ethane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and Sn(II) Cl2 and Fe(II) sulphate. They may be produced as solution or dragee. The Sn(II), Fe(II) and Cr(II) salts serve as reducing agent for the eluated pertechnetate 99m. Glucose or NaCl may be used as filler. (orig./PW)

Preparates for the production of technetium 99m radiodiagnostics

International Nuclear Information System (INIS)

Schmidt-Dunker, M.; Greb, W.

1977-01-01

The preparates serve the production of Tc 99m radiodiagnostics for the scintiscanning of bones or calcareous tumors, muscle tissue or arterial sclerosis. They consist of mixtures of a carboxy phosphonic acid and/or carboxy phosphonate or its water-soluble salts, as well as 1-5 wt.% of a Sn(II), Fe(II) or Cr(II) salt. The mixture has a pH valve of 3 to 9. The preparates are in particular of phosphons-ethane-1,2-dicarbonic acid (mixture of di/trisodium slat of 2:1) an SnCl 2 ; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodiium salt 2:1) and chromium (II) chloride; 2- phosphons-butane-1,2,4-tricarbonic acid (trisodium salt) and iron(II) sulphate; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and Sn(II) chloride; 1-phosphons-propane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and 2-phosphono-butane-1,2,4-tricarbonic acid (trisodium salt) and F(II) sulphate; or phosphons-ethane-1,2-dicarbonic acid (di/tri-sodium salt 2:1) and Sn(II) Cl 2 and Fe(II) sulphate. They many be produced as solution or dragee. The Sn(II), Fe(II) and Cr(II) salts serve as reducing agent for the eluated pertechnetate 99m. Glucose or NaCl may be used as filler. (DG) 891 HP [de

Bone marrow scintigraphy using /sup 111/Indium chloride in patients with aplastic anemia

Energy Technology Data Exchange (ETDEWEB)

Mabuchi, Nobuhisa; Kumano, Machiko; Matsumoto, Fumiko; Arita, Shigehiro; Nakagawa, Kenichi; Fujii, Koichi; Yoshioka, Hiroyasu; Hamada, Tatsumi; Ishida, Osamu

1987-12-01

Bone marrow scintigraphy using /sup 111/Indium chloride (/sup 111/In-chloride) was performed in 18 patients with aplastic anemia. The scintigrams were taken 48 hours after an intravenous injection of /sup 111/In-chloride 3 mCi. The distribution patterns on scintigram were classified into 5 types: Type I (4 cases) showed no accumulation, Type II (6 cases) showed low accumulation in usual bone marrow sites. Type III (7 cases) showed island-like distribution in bone marrow sites. Type IV, although no case was included in the 18 patients, shows uneven distribution between pelvis and sternum or vertebrae. Type V (one case) showed almost normal accumulation in usual bone marrow sites. Bone marrow uptake of /sup 111/In-chloride correlated well with the cellularity of bone marrow. There was a tendency for the cases of markedly increased saturated iron-binding capacity to show increased renal activity. In type III, both the percentage of cases who had been treated and the count of reticulocytes were higher than those in the other types, which suggested that island-like distribution on scintigram showed the regeneration responded to the therapy, and related to the erythropoietic function.

A comparative study of all-vanadium and iron-chromium redox flow batteries for large-scale energy storage

Science.gov (United States)

Zeng, Y. K.; Zhao, T. S.; An, L.; Zhou, X. L.; Wei, L.

2015-12-01

The promise of redox flow batteries (RFBs) utilizing soluble redox couples, such as all vanadium ions as well as iron and chromium ions, is becoming increasingly recognized for large-scale energy storage of renewables such as wind and solar, owing to their unique advantages including scalability, intrinsic safety, and long cycle life. An ongoing question associated with these two RFBs is determining whether the vanadium redox flow battery (VRFB) or iron-chromium redox flow battery (ICRFB) is more suitable and competitive for large-scale energy storage. To address this concern, a comparative study has been conducted for the two types of battery based on their charge-discharge performance, cycle performance, and capital cost. It is found that: i) the two batteries have similar energy efficiencies at high current densities; ii) the ICRFB exhibits a higher capacity decay rate than does the VRFB; and iii) the ICRFB is much less expensive in capital costs when operated at high power densities or at large capacities.

Persistent pollution of Warta river catchment with chromium: case study from central Poland

Science.gov (United States)

Hermanski, S.; Lukaczynski, I.; Nikiel, G.; Mizera, J.; Dulinski, M.; Kania, J.; Rozanski, K.; Szklarczyk, T.; Wachniew, P.; Witczak, S.; Zurek, A.

2012-04-01

Upper reaches of the Warta river, the third largest river in Poland, are located in a densely populated and industrialized area, with presence of heavy industry going back to the second half of the XIX century. Industrial activities include iron smelters in towns of Częstochowa and Zawiercie, large chemical plants (Rudniki and Aniolow) producing predominantly chromium compounds, paper and textile industry, as well as large number of small enterprises specialized in metal coatings (nickel and chromium). Until the 1960s all the industrial and municipal effluents in the region were discharged into the Warta river and its tributaries. Solid wastes were dumped on the surface, mostly without appropriate cover and isolation. This resulted in progressive contamination of surface waters and groundwater with heavy metals, mostly chromium. The upper reaches of the Warta river are located on top of upper Jurassic Major Groundwater Basin (MGWB 326 which is one of four most important groundwater reservoirs in Poland. Almost all potable water demands in the area (ca. 340,000 inhabitants, 800 factories and enterprises) are covered by MGWB 326 (50 deep wells with the average extraction rate of 57,000 m3/d). As the MGWB 326 is mostly phreatic, it has been recognized since long time that persistent pollution of the upper catchment of the Warta river with heavy metals may pose serious thread to quality of this important groundwater resource. In this presentation we summarize the work carried out to date, focused on characterization of the extent and understanding of the mechanisms of pollution of surface water, sediments and groundwater in MGWB 326 with chromium. Historical monitoring data of the levels of chromium in the Warta river and its tributaries are presented, supplemented by the results of measurements of Cr loads in Warta over-bank deposits and Cr levels in groundwater production wells in the area. Three conceptual models of spreading of chromium in the catchment of Warta

Effect of chromium toxicity on germination and early seedling growth ...

African Journals Online (AJOL)

USER

2010-07-19

Jul 19, 2010 ... germination and early seedling growth of melon (Cucumis melo L.). Chromium ... chromium on seed germination and seedling growth- biomass in early ..... such critical regulatory mechanisms are likely to operate in seeds at ...

21 CFR 184.1297 - Ferric chloride.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ferric chloride. 184.1297 Section 184.1297 Food and... Substances Affirmed as GRAS § 184.1297 Ferric chloride. (a) Ferric chloride (iron (III) chloride, FeC13, CAS Reg. No. 7705-08-0) may be prepared from iron and chlorine or from ferric oxide and hydrogen chloride...

Detergents and bleaches are sources of chromium contact dermatitis in Israel

DEFF Research Database (Denmark)

Ingber, A; Gammelgaard, Bente; David, M

1998-01-01

Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products...... ppm, it is concluded that these consumer products may be the cause of the high incidence of chromium sensitivity in Israel....

Serum chromium concentrations in type 2 diabetic patients attending ...

African Journals Online (AJOL)

A highly refined diet that contains too few micronutrients has been recognized as the dominant factor in the rising incidence of diabetes and other insulin related conditions. Among the missing micronutrients, chromium has the greatest impact on insulin response. The objective of this study was to determine serum chromium ...

Potassium Supplementation Prevents Sodium Chloride Cotransporter Stimulation During Angiotensin II Hypertension.

Science.gov (United States)

Veiras, Luciana C; Han, Jiyang; Ralph, Donna L; McDonough, Alicia A

2016-10-01

Angiotensin II (AngII) hypertension increases distal tubule Na-Cl cotransporter (NCC) abundance and phosphorylation (NCCp), as well as epithelial Na(+) channel abundance and activating cleavage. Acutely raising plasma [K(+)] by infusion or ingestion provokes a rapid decrease in NCCp that drives a compensatory kaliuresis. The first aim tested whether acutely raising plasma [K(+)] with a single 3-hour 2% potassium meal would lower NCCp in Sprague-Dawley rats after 14 days of AngII (400 ng/kg per minute). The potassium-rich meal neither decreased NCCp nor increased K(+) excretion. AngII-infused rats exhibited lower plasma [K(+)] versus controls (3.6±0.2 versus 4.5±0.1 mmol/L; Pblood pressure did not significantly decrease. Epithelial Na(+) channel subunit abundance and cleavage increased 1.5- to 3-fold in both A1K and A2K; ROMK (renal outer medulla K(+) channel abundance) abundance was unaffected by AngII or dietary K(+) In summary, the accumulation and phosphorylation of NCC seen during chronic AngII infusion hypertension is likely secondary to potassium deficiency driven by epithelial Na(+) channel stimulation. © 2016 American Heart Association, Inc.

Effect of supplementing finishing pigs with different sources of chromium on performance and meat quality

Directory of Open Access Journals (Sweden)

Louise Manha Peres

2014-07-01

Full Text Available The objective was to evaluate the dietary supplementation of different sources of chromium (inorganic: chromium sulfate and chelated: chromium-methionine during the finishing period of pigs to obtain improvements in the animal performance, and carcass and meat quality. The statistical design was randomized blocks, where 44 barrows, with an initial weight 60.49±5.12 kg, were divided into four blocks (heavier, heavy, light and lighter according to initial weight. The experimental diets were isoenergetic and isonutrient, except for the chromium level. The treatments were divided as follows: control (without chromium, control + 200 ppb of inorganic chromium (chromium sulfate, and control + 200 ppb of chelated chromium (chromium-methionine. In the performance measures, the stall was considered the experimental unit and in the blood parameters, carcass and meat evaluations each animal constituted the experimental unit. Animals were slaughtered when they reached the final average weight of 107.23±5.23 kg. Blood samples were collected and tested for blood parameters (cholesterol, triglycerides and glucose as well as carcass quality (hot and cold weights, yield, loin-eye area, muscle depth and backfat thickness and meat quality (initial and final pH, drip loss, color, chemical composition and lipid oxidation parameters. Chromium-methionine supplementation provides a greater daily weight gain only compared with the animals that are not supplemented with chromium, because feed conversion is better as compared with the other treatments. After 24 hours of storage, the meat from pigs supplemented either with chromium-methionine or with chromium sulfate presents lower lipid oxidation than that from non-supplemented animals. However, after three days of storage, only chromim-methionine is effective in reducing lipid oxidation.

Anthropogenic Chromium Emissions in China from 1990 to 2009

Science.gov (United States)

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

Experimental skin deposition of chromium on the hands following handling of samples of leather and metal

DEFF Research Database (Denmark)

Bregnbak, David; Thyssen, Jacob P.; Jellesen, Morten Stendahl

2016-01-01

Background: Chromium is an important skin sensitizer. Exposure to it has been regulated in cement, and recently in leather. Studies on the deposition of chromium ions on the skin as a result of handling different chromium-containing materials are sparse, but could improve the risk assessment...... of contact sensitization and allergic contact dermatitis caused by chromium. Objectives: To determine whether the handling of chromium-containing samples of leather and metal results in the deposition of chromium onto the skin. Methods: Five healthy volunteers participated. For 30 min, they handled samples...... of leather and metal known to contain and release chromium. Skin deposition of chromium was assessed with the acid wipe sampling technique. Results: Acid wipe sampling of the participants' fingers showed chromium deposition on the skin in all participants who had been exposed to leather (range 0.01–0.20 µg...

77 FR 6627 - National Emission Standards for Hazardous Air Pollutant Emissions: Hard and Decorative Chromium...

Science.gov (United States)

2012-02-08

... aluminum to provide resistance to corrosion. The chromium anodizing process is used to coat aircraft parts... Electroplating and Chromium Anodizing Tanks; and Steel Pickling-HCl Process Facilities and Hydrochloric Acid... Decorative Chromium Electroplating and Chromium Anodizing Tanks; and Steel Pickling-HCl Process Facilities...

Optimization of chromium biosorption in aqueous solution by marine ...

African Journals Online (AJOL)

Optimization of a chromium biosorption process was performed by varying three independent variables pH (0.5 to 3.5), initial chromium ion concentration (10 to 30 mg/L), and Yarrowia lipolytica dosage (2 to 4 g/L) using a Doehlert experimental design (DD) involving response surface methodology (RSM). For the maximum ...

Chromium in Postmortem Material.

Science.gov (United States)

Dudek-Adamska, Danuta; Lech, Teresa; Konopka, Tomasz; Kościelniak, Paweł

2018-04-17

Recently, considerable attention has been paid to the negative effects caused by the presence and constant increase in concentration of heavy metals in the environment, as well as to the determination of their content in human biological samples. In this paper, the concentration of chromium in samples of blood and internal organs collected at autopsy from 21 female and 39 male non-occupationally exposed subjects is presented. Elemental analysis was carried out by an electrothermal atomic absorption spectrometer after microwave-assisted acid digestion. Reference ranges of chromium in the blood, brain, stomach, liver, kidneys, lungs, and heart (wet weight) in the population of Southern Poland were found to be 0.11-16.4 ng/mL, 4.7-136 ng/g, 6.1-76.4 ng/g, 11-506 ng/g, 2.9-298 ng/g, 13-798 ng/g, and 3.6-320 ng/g, respectively.

Dynamic electrochemical measurement of chloride ions

NARCIS (Netherlands)

Abbas, Yawar; de Graaf, Derk B.; Olthuis, Wouter; van den Berg, Albert

2016-01-01

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement,

Reaction of calcium chloride with alkali metal chlorides in melts

International Nuclear Information System (INIS)

Savin, V.D.; Mikhajlova, N.P.

1984-01-01

Thermochemical characteristics of CaCl 2 reaction with sodium, potassium, rubidium and cesium chlorides in melts at 890 deg C are determined. The values of formation enthalpies of infinitely diluted by CaCl 2 solutions (ΔH) in the chloride row increase from -22 in NaCl to -47 kJ/mol of CaCl 2 in CsCl. With increasing the concentration of calcium chloride in the solution the ΔH values decrease. The regularities of separation from the solution of the CaCl 2 -CsCl system at 890 deg C of the CaCl 2 x CsCl in solid are studied. Formation enthalpies under the given conditions constitutes -70+-3 kJ/mol

The Mechanism of Redox Reaction between Palladium(II Complex Ions and Potassium Formate in Acidic Aqueous Solution

Directory of Open Access Journals (Sweden)

Wojnicki M.

2017-06-01

Full Text Available The kinetics studies of redox reaction between palladium(II chloride complex ions and potassium formate in acidic aqueous solutions was investigated. It was shown, that the reduction reaction of Pd(II is selective in respect to Pd(II complex structure. The kinetic of the process was monitored spectrophotometrically. The influence of chloride ions concentration, Pd(II initial concentration, reductant concentration, ionic strength as well as the temperature were investigated in respect to the process dynamics. Arrhenius equation parameters were determined and are equal to 65.8 kJ/mol, and A = 1.12×1011 s−1.

Chromium(VI) release from leather and metals can be detected with a diphenylcarbazide spot test

DEFF Research Database (Denmark)