Journal articles: 'Chrome sulfure'

1

Lafond, A., and A. Meerschaut. "Préparation, détermination structurale et propriétés magnétiques d'un nouveau composé lamellaire incommensurable: Le sulfure de gadolinium et de chrome." Materials Research Bulletin 28, no. 10 (October 1993): 979–87. http://dx.doi.org/10.1016/0025-5408(93)90135-z.

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Vialta, Airton, Cleide F. Catani, Renato B. Junior, and João L. Azevedo. "Isolation and characterization of selenate resistant mutants of Acremonium chrysogenum." Brazilian Archives of Biology and Technology 42, no. 3 (1999): 369–74. http://dx.doi.org/10.1590/s1516-89131999000300016.

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Mutants unable to convert exogenous sulfate to sulfite were isolated using the toxic analogue selenate. Three of twenty-eight isolated mutants were chromate sensitive. They showed a possible lesion in the gene that codes the ATP sulfurylase. The others were chromate resistant, and probably had a lesion in one or both of the genes that code the sulfate permease. Methionine increased the resistance levels to selenate. In addition, the frequency of spontaneous mutants obtained in a medium containing methionine was higher (between 2.4 x 10-6 and 18.0 x 10-6) than that obtained using a medium without any intentional source of sulfur (between 0.7 x 10-6 and 5.0 x 10-6). The original strain, as well as the mutants, were able to grow in a sulfur-free liquid medium even after 4 consecutive inoculation procedures. These results indicated the existence of sulfur traces in the medium and/or an efficient intracellular storage system. There was no significant difference between cephalosporin C production in mutants and the original strain.

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Liu, Cheng Jun, Jie Qi, and Mao Fa Jiang. "Experimental Study on Sulfuric Acid Leaching Behavior of Chromite with Different Temperature." Advanced Materials Research 361-363 (October 2011): 628–31. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.628.

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Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of atmospheric pressure and the addition of oxidant A. And the leaching rate of chromium and iron would be 98.5% and 71.9%, respectively. The sulfuric acid leaching processes with different temperature were systematically studied by chemical analysis and phase analysis. The results showed that, with the increase of reaction temperature, the leaching rate of chromium would increase gradually, but the leaching rate of iron increased at first and then decreases and reached its maximum at 140°C. When the temperature > 160°C, the phases of the leaching residue were magnesium iron silicate and a few of silica, no chromohercynite, chrompicotite and magnesioferrite existed in the chromite. The leaching solution of sulfuric acid leaching process could be used for preparing the basic chrome sulfate, and there is no Cr6+ in the leaching residue and solution. The results would provide theoretical guidance for solving environmental pollution problem of Cr6+ in traditional chromate production process.

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Yatribi, A., and A. Nejmeddine. "Impact écotoxicologique du traitement chimique des eaux usées de tanneries: Analyse technico-économique." Revue des sciences de l'eau 13, no. 2 (April 12, 2005): 107–18. http://dx.doi.org/10.7202/705384ar.

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La toxicité des eaux usées du tannage au chrome et d'épilage-pelanage, avant et après traitement, a été évaluée par test Daphnia pulex. Cette évaluation a été déterminée à partir des équations de corrélation linéaires. Les résultats obtenus montrent que le tannage au chrome et l'épilage-pelanage présentent une toxicité élevée avec des valeurs des CI50 24h respectives de 0,15 et 3,36. Cette toxicité élevée pourrait être expliquée par la charge de ces effluents en chrome, en sulfures et en matière organique. Après traitement par précipitation chimique, la CI50 24h a connu une importante augmentation. Elle est passée de 0,15 à 26,58 et de 3,36 à 11,1 respectivement pour le tannage au chrome et l'épilage-pelanage. Par conséquent, ces effluents traités peuvent être classés comme rejets peu toxiques. Cette diminution de la toxicité est liée surtout à l'abattement des MES (95 %), de la DCO (55 %), de Cr (90 %) et des sulfures (50 %). Ce traitement a donc, un double intérêt; le premier est environnemental, le second est économique du fait de la possibilité de recyclage du chrome récupéré dans le tannage du cuir. En effet, l'application expérimentale du chrome dans le tannage a montré un résultat similaire à celui obtenu par le produit commercial. Ainsi, suite à une analyse technico-économique, le bénéfice réalisé par cette opération est estimé à 3112,50 $ par 1000 tonnes par an.

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Belal, Md, and Abu T. Khan. "Oxidative cross coupling reaction mediated by I2/H2O2: a novel approach for the construction of fused thiazole containing coumarin derivatives." RSC Advances 5, no. 126 (2015): 104155–63. http://dx.doi.org/10.1039/c5ra20405d.

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Various 2-phenyl-4H-chromeno(3,4-d)thiazol-4-one derivatives have been synthesized through C–H bond activation using sodium sulfide as a source of sulfur atoms and by employing I₂ as a catalyst and H₂O₂ as the terminal oxidant.

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Dawara, Latika, S. C. Joshi, and R. V. Singh. "Synthesis, Characterization, and Antimicrobial and Antispermatogenic Activity of Bismuth(III) and Arsenic(III) Derivatives of Biologically Potent Nitrogen and Sulfur Donor Ligands." International Journal of Inorganic Chemistry 2012 (April 22, 2012): 1–9. http://dx.doi.org/10.1155/2012/372141.

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A series of Bi(III) and As(III) complexes with two N∩S donor ligands, 1-(4-chloro-2-oxo-2H-chromen-3-yl)-methylene)-thiosemicarbazide (L1H) and N′-[1-(2-oxo-2H-chrome-3yl-ethylidene]-hydrazinecarbodithionic acid benzyl ester (L2H) have been synthesized by the reaction of BiCl3 and Ph3As with ligands in 1 : 1 and 1 : 2 molar ratios. All the synthesized compounds were characterized by elemental analyses, melting point determinations, and a combination of electronic, IR, 1H NMR, 13C NMR spectroscopic techniques, and X-ray diffraction for structure elucidation. In order to evaluate the effect of metal ions upon chelation, both the ligands and their complexes have been screened for their antimicrobial activity against the various pathogenic bacterial and fungal strains. The metal complexes have shown to be more antimicrobial against the microbial species as compared to free ligands. Both the ligands and their corresponding metal complexes have been tested for their antifertility activity in male albino rats. The marked reduction in sperm motility and density resulted in infertility. Significant alterations were found in biochemical parameters of reproductive organs in treated animals as compared to control group. It is concluded that all these effects may finally impair the fertility of male rats.

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Yanjiao, Gao, Huang Runzhu, and Song Tiehong. "Using Fenton Oxidation Method to Advanced Treatment of Landfill Leachate." Open Chemical Engineering Journal 9, no. 1 (July 31, 2015): 58–61. http://dx.doi.org/10.2174/1874123101509010058.

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Hydrogen peroxide and ferrous sulfate were used to advanced treatment of landfill leachate effluent from biochemical tanks. Some influences on removing COD and chroma including the pH value of solution, the dosage of ferrous sulfate, the dosage of hydrogen peroxide and reaction time were investigated. The test results showed that for removal of COD and chroma the optimal pH was 3.0, the best ferrous sulfate and hydrogen peroxide dosage was 1500mg/L, 20mL/L respectively, and the optimal reaction time was 60min. Under optimal conditions, COD and chroma removal rate could reach 79.7% and 95.2% respectively.

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8

Sharifi, Majid, Najmoddin Arab, and Gholamreza Khalaj. "Prediction of Toughness through Evaluation of Alloying Elements Distribution Pattern at Heat-Affected Zone in Submerged-Arc Welding Process of API X70 Steel." Applied Mechanics and Materials 467 (December 2013): 35–40. http://dx.doi.org/10.4028/www.scientific.net/amm.467.35.

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Six 56" × 19.8 mm, API X70 PSL2 pipes were produced from three different plate suppliers and then three samples in pipe transverse direction and perpendicular to welding seam were taken out from welding area of each supplier. Sampling carried out from weld metal, HAZ and base metal of each sample, then all 27 prepared samples were analyzed. Afterwards the amounts of 14 alloying elements were considered. The results showed that content of Carbon, Sulfur, Boron, Phosphorous, Copper, Manganese, Aluminum, Titanium and Molybdenum have been increased in the HAZ and Silicon, Nickel, Chrome, Vanadium and Niobium decreased. So it is predicted that an increase in Carbon, Aluminum, Phosphorous, Sulfur and Boron content, also a decrease in Silicon, Chrome and Nickel will cause a drop in the HAZ toughness and an increase in Titanium, Manganese, Copper and Molybdenum content, also decrease in Vanadium and Niobium will cause a rise in HAZ toughness.

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9

Khan, M. Rafiq. "Techno-Economic Evaluation of Chromium Recovery Pilot Plant Installed at Kasur Tanneries Complex, Pakistan." Pakistan Development Review 46, no. 4II (December 1, 2007): 1155–66. http://dx.doi.org/10.30541/v46i4iipp.1155-1166.

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Chromium metal is widely used as a tanning agent worldwide. The process called chrome-tanning is accomplished in three steps: Pickling, Tanning and Basification1 (Pakistan Tanners Association). Chromium sulfate is the most widely used chemical in this process. Approximately, 60-70 percent of chromium sulfate applied is taken up by the hides and skins, while its 30 to 40 percent remains un-used and is discharged as a component of wastewater into natural water bodies such as rivers, streams, etc., which has adverse environmental impacts on living organisms particularly to humans and animals [Weitz and Luxenberg (n.d.)], and water animals such as fish [Eisler (1986)]. The diseases especially encountered in humans, are of nervous disorders. The pollution from tanneries effluent particularly their chromium component has formed the basis that many developed countries have banned tanning on their soils. Chrome tanned leather, being the need of people all over the world, has the edge that its manufacture cannot be stopped. This has given some economic advantage to some developing countries including Pakistan to manufacture leather and export it to the developed countries. To sustain, different methods have been developed to recover chromium from the tannery effluents before their drainage in the natural water bodies. A few examples of these methods are High Chrome Exhaustion, Direct Recycling of the Spent Tanning Float and Chrome Recovery and Reuse [Arrafay Labs (2003)].

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10

Garcia, Edivaldo E., Cláudia C. M. Kimura, Ariovaldo C. Martins, Gisele O. Rocha, and Jorge Nozaki. "Chromatographic characterization of products isolated from chrome shavings." Brazilian Archives of Biology and Technology 42, no. 3 (1999): 281–90. http://dx.doi.org/10.1590/s1516-89131999000300003.

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Gel permeation chromatography and high performance liquid chromatography were employed for separation and chemical characterization of products isolated from chrome shavings. After enzymatic hydrolysis, the products isolated were peptides of higher molecular weight. Peptides of lower molecular weight and free aminoacids were the main products using sulfuric acid in chrome shavings solubilization. Glycine (17%) , glutamic acid (10.6%) , alanine (9.2%) , and arginine (8.2%) were the principal amino acids found. Phenylalanine(1.8%) was the main aromatic amino acid , while tryptophane was completely absent.

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11

Choi, Min Young, Y. Choi, J. I. Choe, Man Kim, and Sik Chol Kwon. "Effect of Solution Chemistry and Electroplating Conditions on the Deposition Rate and Wear Resistance of Eco-Friendly Trivalent Chromium Layers." Materials Science Forum 475-479 (January 2005): 4005–8. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.4005.

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Chromium chloride (CrCl3) or chromium sulfate(Cr2(SO4)3) content increased trivalent chrome deposition rate. The addition of formic acid and the relative content change of potassium hydroxide decreased the trivalent chrome deposition rate. Industrially applicable trivalent chromium layers with more than 200 µm thick were well prepared at the conditions of pH with the range of 1.3-1.8, electrical current density of 5.0-5.6 A/cm2 and applied voltage of 4.0-5.9V. Average microhardnesses of the chromium layers prepared in the chromium chloride and chromium sulfate solutions are about 803-820 and 700-712 Hv, respectivevly. The wear resistance of the trivalent chromium layers was improved by plating voltage which was related to residual compressive stress on the chomium layer.

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12

Kiseleva, Olga N., Evgeniya V. Airiyants, Dmitriy K. Belyanin, and Sergey M. Zhmodik. "Podiform Chromitites and PGE Mineralization in the Ulan-Sar’dag Ophiolite (East Sayan, Russia)." Minerals 10, no. 2 (February 7, 2020): 141. http://dx.doi.org/10.3390/min10020141.

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In this paper, we present the first detailed study on the chromitites and platinum-group element mineralization (PGM) of the Ulan-Sar’dag ophiolite (USO), located in the Central Asian Fold Belt (East Sayan). Three groups of chrome spinels, differing in their chemical features and physical–chemical parameters, under equilibrium conditions of the mantle mineral association, have been distinguished. The temperature and log oxygen fugacity values are, for the chrome spinels I, from 820 to 920 °C and from (−0.7) to (−1.5); for chrome spinels II, 891 to 1003 °C and (−1.1) to (−4.4); and for chrome spinels III, 738 to 846 °C and (−1.1) to (−4.4), respectively. Chrome spinels I were formed through the interaction of peridotites with mid-ocean ridge basalt (MORB)-type melts, and chrome spinels II were formed through the interaction of peridotites with boninite melts. Chrome spinels III were probably formed through the interaction of andesitic melts with rocks of an overlying mantle wedge. Chromitites demonstrate the fractionated form of the distribution of the platinum-group elements (PGE), which indicates a high degree of partial melting at 20–24% of the mantle source. Two assemblages of PGM have been distinguished: The primary PGE assemblage of Os-Ir-Ru alloys-I, (Os,Ru)S2, and IrAsS, and the secondary PGM assemblage of Os-Ir-Ru alloys-II, Os0, Ru0, RuS2, OsS2, IrAsS, RhNiAs with Ni, Fe, and Cu sulfides. The formation of the secondary phases of PGE occurred upon exposure to a reduced fluid, with a temperature range of 300–700 °C, log sulfur fugacity of (−20), and pressure of 0.5 kbar. We have proposed a scheme for the sequence of the formation and transformation of the PGMs at various stages of the evolution of the Ulan-Sar’dag ophiolite.

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13

Lin, Xiaoju, Gaoling Wei, Xiaoliang Liang, Jing Liu, Lingya Ma, and Jianxi Zhu. "The Competitive Adsorption of Chromate and Sulfate on Ni-Substituted Magnetite Surfaces: An ATR-FTIR Study." Minerals 11, no. 1 (January 18, 2021): 88. http://dx.doi.org/10.3390/min11010088.

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With similar chemical properties and geometrical configurations, sulfate and chromate display interesting competitive adsorption on mineral surfaces. Although such issues have been investigated on several Fe (hydr)oxide surfaces, e.g., ferrihydrite, goethite and hematite, the competitive adsorption on magnetite surfaces and the constraint mechanism have seldom been studied. This impedes the understanding of the transfer and fate of chromate and sulfate on magnetite surfaces, as magnetite is not only a useful adsorbent but also an efficient reductant to decrease the mobility and toxicity of chromium. In the present study, the geometries of the competitive adsorption of chromate and sulfate on Ni-substituted magnetite surfaces over a pH range of 4–9 were investigated using in situ attenuated total reflectance Fourier transform infrared spectroscopy and two-dimensional correlation analysis. In individual adsorption, nonprotonated monodentate mononuclear (NMM) complexes dominated chromate adsorption, accompanied by a few bidentate binuclear (BB) complexes. For sulfate, NMM complexes and outer-sphere (OS) species predominated under acidic and neutral–alkaline conditions, respectively. The above variation in adsorption configuration resulted in the different adsorption competitiveness between chromate and sulfate at different pH values. Specifically, the NMM complexes of chromate were substituted by NMM sulfate complexes under acidic conditions and vice versa. However, under neutral and alkaline conditions, the OS species of sulfate scarcely affected the adsorption of chromate. The adsorption affinity of chromate and sulfate on Ni-substituted magnetite increased in the following order: OS complex (sulfate) < NMM complexes (chromate) < NMM complexes (sulfate).

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CHOI, Y., N. I. CHO, and J. I. CHOE. "QUANTITATIVE STUDY OF SURFACE MORPHOLOGY BY ATOMIC FORCE MICROSCOPY." International Journal of Modern Physics B 16, no. 28n29 (November 20, 2002): 4395–400. http://dx.doi.org/10.1142/s0217979202015480.

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Atomic force microscopy was applied to study the formation and growth mechanism of thin multilayers of chromium-molybdenum and chrome prepared by electro-pulse plating, respectively. The chromium-molybdenum and chrome layers were prepared using direct current density of 1.6 mA.mm -2 and pulse currents with on-off time from 5 to 2000 ms in the bath containing 300g l-1 of chromic acid and 75g l-1 ammonium molybdate, and 250g l-1 of chromic acid and 5g l-1 of sulfuric acid, respectively. The higher current density enhanced nucleation rate which resulted in refining grain size. The micro-hardness of the pulse plated chrome and chromium-molybdenum alloy layers increased with the duration of on-off time and pulse current density. The average surface roughness of chrome layer is increased with increasing on/off time ratio for a given peak current density and voltage because the growth and dissolution mainly occurs during on-time and off-time, respectively. However, the average surface roughness of chromium-molybdenum alloy layer is decreased with increasing on/off time ratio for a given peak current density and voltage because the alloying element in the layer.

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Mahaputra, Mahaputra, and Tarmizi Tarmizi. "Pengaruh Pengelasan Tungsten Inert Gas (TIG) terhadap Komposisi Kimia Logam yang Dianalisa dengan Metoda Optical Emission Spectrometry(OES)." Jurnal Riset Teknologi Industri 8, no. 15 (August 25, 2016): 55–65. http://dx.doi.org/10.26578/jrti.v8i15.1553.

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Spectrophotometer is an instrument use to measure the absorbance of a chemical com-position by passing light with a certain wavelength at a certain prism. Absorbance values of the light that is passed will be proportional to the concentration of the solution. This research use Optical Emission Spectrometry (OES), a method to testing chemical composition and Tungsten Inert Gas (TIG). TIG is a welding method using a tungsten electrode (not an added substance) an electric arc that occurs between the end of the tungsten electrode and the base material is a heat source. For welding, extended size method used to support testing of chemical composition and added thickness to analyze its effect on the test results chemical composition. The results of the initial test, extended size and added thicknes test indicate that the results of chemical composition of the metal being tested does not significantly change. Here is the initial test result (%) carbon: 0.447; silicon: 0.499; manganese: 0.423; phosphorus: 0.0717; sulfur: 0.237; nickel: 0.354; chrom: 12.4; molybdenum: 0.466, and for the results of the extended size method (%) carbon: 0.402; silicon: 0.435; manganese: 0.406; phosphorus: 0.0810; sulfur: 0.0424; nickel: 0,320; chrom: 12.6; molybdenum: 0.463, the added thickness method (%) carbon: 0.428; silicon: 0,467; manganese: 0.411; phosphorus: 0.0674; sulfur: 0.0553; nickel: 0.332; chrom: 12.6; molyb-denum: 0,462.ABSTRAK Spektrofotometer adalah alat yang digunakan untuk mengukur absorbansi suatu senyawa kimia dengan cara melewatkan cahaya dengan panjang gelombang tertentu pada suatu prisma. Nilai absorbansi dari cahaya yang dilewatkan akan sebanding dengan konsentrasi larutan tersebut. Metoda pengujian komposisi kimia yang digunakan pada penelitian ini adalah metoda Optical Emission Spectrometry (OES), sedangkan metoda pengelasan menggunakan Tungsten Inert Gas (TIG). TIG adalah metode pengelasan yang menggunakan elektroda wolfram (bukan bahan tambah) dimana busur listrik yang terjadi antara ujung elektroda wolfram dan bahan dasar merupakan sumber panas. Dalam pengelasan, metoda extended size digunakan untuk mendukung peng-ujian komposisi kimia dan added thickness serta untuk menganalisa pengaruhnya terhadap hasil pengujian komposisi kimia. Hasil pengujian awal, perlakuan extended size dan added thickness menunjukkan komposisi kimia logam yang diuji tidak mengalami perubahan secara signifikan (%) adalah sebagai berikut: carbon: 0,447; silicon: 0,499; mangan: 0,423; phospor: 0,0717; sulfur: 0,237; nickel: 0,354; chrom: 12,4; molybdenum: 0,466, dan untuk hasil uji komposisi kimia metoda extended size (%) carbon: 0,402; silicon: 0,435; mangan: 0,406; phospor: 0,0810; sulfur: 0,0424; nickel: 0,320; chrom: 12,6; molybdenum: 0,463, sedangkan untuk metoda added thickness (%) carbon: 0,428; silicon: 0,467; mangan: 0,411; phospor: 0,0674; sulfur: 0,0553; nickel: 0,332; chrom: 12,6; molybdenum: 0,462.Kata kunci : ptical Emission Spectrometry (OES), komposisi kimia, pengelasan, extended size, added thickness.

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16

Acosta-Navarrete, Yaned M., Yhoana L. León-Márquez, Karina Salinas-Herrera, Irvin E. Jácome-Galarza, Víctor Meza-Carmen, Martha I. Ramírez-Díaz, and Carlos Cervantes. "Expression of the six chromate ion transporter homologues of Burkholderia xenovorans LB400." Microbiology 160, no. 2 (February 1, 2014): 287–95. http://dx.doi.org/10.1099/mic.0.073783-0.

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The chromate ion transporter (CHR) superfamily comprises transporters that confer chromate resistance by extruding toxic chromate ions from cytoplasm. Burkholderia xenovorans strain LB400 has been reported to encode six CHR homologues in its multireplicon genome. We found that strain LB400 displays chromate-inducible resistance to chromate. Susceptibility tests of Escherichia coli strains transformed with cloned B. xenovorans chr genes indicated that the six genes confer chromate resistance, although under different growth conditions, and suggested that expression of chr genes is regulated by sulfate. Expression of chr genes was measured by quantitative reverse transcription-PCR (RT-qPCR) from total RNA of B. xenovorans LB400 grown under different concentrations of sulfate and exposed or not to chromate. The chr homologues displayed distinct expression levels, but showed no significant differences in transcription under the various sulfate concentrations tested, indicating that sulfate does not regulate chr gene expression in B. xenovorans. The chrA2 gene, encoded in the megaplasmid, was the only chr gene whose expression was induced by chromate and it was shown to constitute the chromate-responsive chrBACF operon. These data suggest that this determinant is mainly responsible for the B. xenovorans LB400 chromate resistance phenotype.

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Biedlingmaier, Susanne, and Ahlert Schmidt. "Sulfate Transport in Normal and S-Deprived Chlorella fusca." Zeitschrift für Naturforschung C 44, no. 5-6 (June 1, 1989): 495–503. http://dx.doi.org/10.1515/znc-1989-5-625.

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Abstract Sulfate uptake into the unicellular green alga Chlorella fusca Shihira et Krauss strain 211-8 b was described as a pH-, temperature-and energy-dependent process. Transport followed triphasic kinetics with Km-values of 1.3 x 10-5, 3.9 x 10-5 and 2.8 x 10-4M. The Hill plot showed coefficients of 1.0 for each uptake isotherm. Sulfate uptake was substantially inhibited by chromate, selenate, sulfite, thiosulfate and tetrathionate. Cysteine and other mercaptides diminished sulfate transport, whereas methionine was not inhibitory. Uptake was sensitive towards inhibitors of photosynthesis and respiration and towards SH-group reagents. Sulfate uptake could be strongly enhanced by polyvalent cations, apparently via reduction of the surface potential. Sulfate uptake in S-deprived algae was markedly different from constitutive sulfate uptake. Time kinetics was not linear but showed an initial rapid phase. Uptake was neither multiphasic nor conformed to simple Michaelis-Menten kinetics. Sulfate uptake was hardly affected by pH and temperature in the suboptimal range. The Arrhenius plot was biphasic with a discontinuity at 38 °C.

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Wang, E. Y., J. T. Cherian, A. Madsen, and R. M. Fisher. "EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching." Proceedings, annual meeting, Electron Microscopy Society of America 53 (August 13, 1995): 538–39. http://dx.doi.org/10.1017/s0424820100139068.

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Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.

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Polyakov, V. N., V. V. Romanov, V. N. Rozov, V. V. Maksimenko, and L. V. Skrypnik. "Sulfide cracking resistance of several steels with diffusion chrome coatings." Soviet Materials Science 28, no. 2 (1993): 205–6. http://dx.doi.org/10.1007/bf00727322.

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Paietta, J. V. "Molecular cloning and analysis of the scon-2 negative regulatory gene of Neurospora crassa." Molecular and Cellular Biology 10, no. 10 (October 1990): 5207–14. http://dx.doi.org/10.1128/mcb.10.10.5207.

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The sulfur regulatory system of Neurospora crassa is composed of a group of highly regulated structural genes (e.g., the gene encoding arylsulfatase) that are under coordinate control of scon+ (sulfur controller) negative and cys-3+ positive regulatory genes. In scon-1 (previously designated sconC) and scon-2 mutants, there is constitutive expression of sulfur structural genes regardless of the sulfur level available to the cells. The scon-2+ gene was cloned by sib selection screening of a cosmid-based gene library. The screening was based on the use of chromate, a toxic sulfate analog, which is transported into scon-2 cells grown on high sulfur but is not transported into cells that have regained normal sulfur regulation. Restriction fragment length polymorphism analysis was used to confirm that the cloned segment mapped to the proper chromosomal location. In wild-type cells, Northern (RNA) blot analysis showed that a 2.6-kilobase scon-2+ transcript was present at a substantial level only under sulfur-derepressing conditions. Kinetic analysis showed that scon-2+ mRNA content increased as the cells became sulfur starved. Further, scon-2+ RNA was detectable in a nuclear transcription assay only under derepressing conditions. In scon-1, the levels of scon-2+ mRNA were found to be constitutive. In the cys-3 regulatory mutant, there was a reduced level of scon-2+ transcript. cys-3+ and ars-1+ mRNAs were present under both derepressing and repressing conditions in the scon-2 mutant. Repeat-induced point mutation-generated scon-2 mutants were identical in phenotype to the known mutant.

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Paietta, J. V. "Molecular cloning and analysis of the scon-2 negative regulatory gene of Neurospora crassa." Molecular and Cellular Biology 10, no. 10 (October 1990): 5207–14. http://dx.doi.org/10.1128/mcb.10.10.5207-5214.1990.

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The sulfur regulatory system of Neurospora crassa is composed of a group of highly regulated structural genes (e.g., the gene encoding arylsulfatase) that are under coordinate control of scon+ (sulfur controller) negative and cys-3+ positive regulatory genes. In scon-1 (previously designated sconC) and scon-2 mutants, there is constitutive expression of sulfur structural genes regardless of the sulfur level available to the cells. The scon-2+ gene was cloned by sib selection screening of a cosmid-based gene library. The screening was based on the use of chromate, a toxic sulfate analog, which is transported into scon-2 cells grown on high sulfur but is not transported into cells that have regained normal sulfur regulation. Restriction fragment length polymorphism analysis was used to confirm that the cloned segment mapped to the proper chromosomal location. In wild-type cells, Northern (RNA) blot analysis showed that a 2.6-kilobase scon-2+ transcript was present at a substantial level only under sulfur-derepressing conditions. Kinetic analysis showed that scon-2+ mRNA content increased as the cells became sulfur starved. Further, scon-2+ RNA was detectable in a nuclear transcription assay only under derepressing conditions. In scon-1, the levels of scon-2+ mRNA were found to be constitutive. In the cys-3 regulatory mutant, there was a reduced level of scon-2+ transcript. cys-3+ and ars-1+ mRNAs were present under both derepressing and repressing conditions in the scon-2 mutant. Repeat-induced point mutation-generated scon-2 mutants were identical in phenotype to the known mutant.

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Jia, Ru-sheng, and Yu-lan Gao. "Experimental Research on Removal of UV254 by PFS in Pi River water with low turbidity." E3S Web of Conferences 194 (2020): 04038. http://dx.doi.org/10.1051/e3sconf/202019404038.

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Through beaker test, it was analyzed the effect on the removal of turbidity, chroma and UV254 in PI River water with low turbidity by poly-ferric sulfate(PFS).The results showed that it has good effect on removing turbidity and chroma by adding PFS, but it was normal to UV254, not exceed 50%,with the increase of PFS dosage, the turbidity and chroma removal trend is similar to that of UV254. For turbidity removal, the optimal dosage of PFS was 70 mg / L, and for UV254 removal, the optimal pH value range is not neutral, and it is speculated that PFS mainly neutralizes pollutants during coagulation in PI River water.

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Aboulhassan, Moulay Abdelazize, Salah Souabi, Abdelrani Yaacoubi, Nourredine Zaim, and Fatima Zohra Bouthir. "Les effluents de tannerie caractérisation et impact sur le milieu marin." Revue des sciences de l'eau 21, no. 4 (October 20, 2008): 463–73. http://dx.doi.org/10.7202/019168ar.

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Résumé Dans ce travail, nous avons caractérisé et évalué l’impact sur le milieu marin des rejets industriels de tannerie. Les résultats montrent que la qualité des eaux usées varie considérablement d’une étape de production à l’autre. Les opérations de prétannage (travail de rivière) sont les plus polluantes avec des teneurs en DCO qui peuvent atteindre 30 000 mg/L. L’analyse des eaux usées au niveau du bassin de collecte, où s’achemine l’ensemble des effluents de l’usine, montre une charge polluante importante et variable avec le temps. La DCO fluctue entre 700 et 3 400 mg/L et les matières en suspension entre 500 et 8 000 mg/L avec des charges polluantes moyennes de 114 et 358 kg/jour respectivement. Ces eaux sont aussi chargées en chrome avec des teneurs qui se situent entre 40 et 115 mg/L, soit une charge de 6,5 kg/jour. La teneur en sulfures varie entre 65 et 160 mg/L. En outre, l’indice de biodégradabilité (DBO5/DCO : 0.1 – 0.2) indique que ce rejet n’est pas facilement biodégradable. L’examen des teneurs en chrome chez des espèces bioindicatrices, la moule Mytilus galloprovincialis et les algues Ulva lactuca et Corallina officinalis, montre l’ampleur des apports en polluants causée par ce type de rejets au niveau de la mer. Les teneurs en chrome au niveau de ces espèces à proximité de point du déversement de ces eaux usées, sont élevées comparées à d’autres points plus éloignés.

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Protsenko, V. S., F. I. Danilov, V. O. Gordiienko, S. C. Kwon, M. Kim, and J. Y. Lee. "Electrodeposition of hard nanocrystalline chrome from aqueous sulfate trivalent chromium bath." Thin Solid Films 520, no. 1 (October 2011): 380–83. http://dx.doi.org/10.1016/j.tsf.2011.07.036.

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Boiko, S. V., L. L. Il'ichev, V. M. Kushnarenko, and V. G. Stavishenko. "Protective properties of pyrolytic chrome coatings in hydrogen sulfide-containing media." Materials Science 29, no. 1 (1993): 104–7. http://dx.doi.org/10.1007/bf00558673.

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Jiménez, Diego, Ramón Martínez-Máñez, Félix Sancenón, José V. Ros-Lis, A. Benito, and Juan Soto. "A New Chromo-chemodosimeter Selective for Sulfide Anion." Journal of the American Chemical Society 125, no. 30 (July 2003): 9000–9001. http://dx.doi.org/10.1021/ja0347336.

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Amat, Anna, Costanza Miliani, and Simona Fantacci. "Structural and electronic properties of the PbCrO4 chrome yellow pigment and of its light sensitive sulfate-substituted compounds." RSC Advances 6, no. 43 (2016): 36336–44. http://dx.doi.org/10.1039/c6ra01444e.

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Chrome Yellows (CY) are a family of synthetic pigments of formula (PbCr_(1−x)S_xO₄) used by van Gogh. We investigate structure/property relations in CY by first-principles methods, providing insight into their possible degradation mechanisms.

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Ardashev, Dmitrii, Nizami Yusubov, Leonid Shipulin, and Anastasiya Degtyareva-Kashutina. "Development of environmental protection system for installation of chrome plating of the internal surfaces of hydraulic drives with hydrostatic guideways." E3S Web of Conferences 193 (2020): 02015. http://dx.doi.org/10.1051/e3sconf/202019302015.

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Electroplating is an electrochemical process when a metal layer is deposited on the surfaces of a product. As an electrolyte, a solution of the salts of the deposited metal is used, the vaporization and micro-spray of which have an extremely negative and dangerous effect on humans and the environment. In this work, we present an environmental protection system for implementing the process of chrome plating of the internal surfaces of a hydraulic drive with hydrostatic guideways is presented. The schematic diagram of the environmental protection system includes the first stage of air purification (drip collector), the second stage of air purification (granular filter), as well as a system of granular filter cleaning and a radial fan. To clean the exhaust air from harmful substances, such as aerosols of chromium oxides and sulfuric acid, as well as water vapor, a comprehensive gas purification system for emissions of pollutants is proposed, consisting of step-by-step cleaning in various devices, including a drip collector with two droplet-breaking elements and a granular filter. The presented design of the environmental protection system equipment of the installation for chrome-plating the internal surfaces of a hydraulic drive with hydrostatic guideways will make it possible to effectively neutralize the air environment by cleaning the air from chrome anhydride vapor and other pollutants.

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Mahmoud, Ahmed S., Nouran Y. Mohamed, Mohamed K. Mostafa, and Mohamed S. Mahmoud. "Effective Chromium Adsorption From Aqueous Solutions and Tannery Wastewater Using Bimetallic Fe/Cu Nanoparticles: Response Surface Methodology and Artificial Neural Network." Air, Soil and Water Research 14 (January 2021): 117862212110281. http://dx.doi.org/10.1177/11786221211028162.

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Tannery industrial effluent is one of the most difficult wastewater types since it contains a huge concentration of organic, oil, and chrome (Cr). This study successfully prepared and applied bimetallic Fe/Cu nanoparticles (Fe/Cu NPs) for chrome removal. In the beginning, the Fe/Cu NPs was equilibrated by pure aqueous chrome solution at different operating conditions (lab scale), then the nanomaterial was applied in semi full scale. The operating conditions indicated that Fe/Cu NPs was able to adsorb 68% and 33% of Cr for initial concentrations of 1 and 9 mg/L, respectively. The removal occurred at pH 3 using 0.6 g/L Fe/Cu dose, stirring rate 200 r/min, contact time 20 min, and constant temperature 20 ± 2ºC. Adsorption isotherm proved that the Khan model is the most appropriate model for Cr removal using Fe/Cu NPs with the minimum error sum of 0.199. According to khan, the maximum uptakes was 20.5 mg/g Cr. Kinetic results proved that Pseudo Second Order mechanism with the least possible error of 0.098 indicated that the adsorption mechanism is chemisorption. Response surface methodology (RSM) equation was developed with a significant p-value = 0 to label the relations between Cr removal and different experimental parameters. Artificial neural networks (ANNs) were performed with a structure of 5-4-1 and the achieved results indicated that the effect of the dose is the most dominated variable for Cr removal. Application of Fe/Cu NPs in real tannery wastewater showed its ability to degrade and disinfect organic and biological contaminants in addition to chrome adsorption. The reduction in chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), Cr, hydrogen sulfide (H2S), and oil reached 61.5%, 49.5%, 44.8%, 100%, 38.9%, 96.3%, 88.7%, and 29.4%, respectively.

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Park, C. H., M. Keyhan, B. Wielinga, S. Fendorf, and A. Matin. "Purification to Homogeneity and Characterization of a Novel Pseudomonas putida Chromate Reductase." Applied and Environmental Microbiology 66, no. 5 (May 1, 2000): 1788–95. http://dx.doi.org/10.1128/aem.66.5.1788-1795.2000.

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ABSTRACT Cr(VI) (chromate) is a widespread environmental contaminant. Bacterial chromate reductases can convert soluble and toxic chromate to the insoluble and less toxic Cr(III). Bioremediation can therefore be effective in removing chromate from the environment, especially if the bacterial propensity for such removal is enhanced by genetic and biochemical engineering. To clone the chromate reductase-encoding gene, we purified to homogeneity (>600-fold purification) and characterized a novel soluble chromate reductase from Pseudomonas putida, using ammonium sulfate precipitation (55 to 70%), anion-exchange chromatography (DEAE Sepharose CL-6B), chromatofocusing (Polybuffer exchanger 94), and gel filtration (Superose 12 HR 10/30). The enzyme activity was dependent on NADH or NADPH; the temperature and pH optima for chromate reduction were 80°C and 5, respectively; and theKm was 374 μM, with aV max of 1.72 μmol/min/mg of protein. Sulfate inhibited the enzyme activity noncompetitively. The reductase activity remained virtually unaltered after 30 min of exposure to 50°C; even exposure to higher temperatures did not immediately inactivate the enzyme. X-ray absorption near-edge-structure spectra showed quantitative conversion of chromate to Cr(III) during the enzyme reaction.

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Wu, Cuiyan, Xiaojun Hu, Biao Gu, Peng Yin, Wei Su, Yaqian Li, Qiujun Lu, Youyu Zhang, and Haitao Li. "A lysosome-targeting colorimetric and fluorescent dual signal probe for sensitive detection and bioimaging of hydrogen sulfide." Analytical Methods 10, no. 6 (2018): 604–10. http://dx.doi.org/10.1039/c7ay02492d.

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In this study, we developed a lysosome-targeting fluorescent probe, 3-(2,4-dinitrophenoxy)-2-(4-morpholinophenyl)-4H-chromen-4-one (DMC), for the detection of hydrogen sulfide (H₂S) based on excited-state intramolecular proton transfer (ESIPT).

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32

Alvarez, Angel H., Rafael Moreno-Sánchez, and Carlos Cervantes. "Chromate Efflux by Means of the ChrA Chromate Resistance Protein from Pseudomonas aeruginosa." Journal of Bacteriology 181, no. 23 (December 1, 1999): 7398–400. http://dx.doi.org/10.1128/jb.181.23.7398-7400.1999.

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ABSTRACT Everted membrane vesicles of Pseudomonas aeruginosaPAO1 harboring plasmid pCRO616, expressing the ChrA chromate resistance protein, accumulated four times more51CrO4 2− than vesicles from plasmidless cells, indicating that a chromate efflux system functions in the resistant strain. Chromate uptake showed saturation kinetics with an apparent Km of 0.12 mM chromate and aV max of 0.5 nmol of chromate/min per mg of protein. Uptake of chromate by vesicles was dependent on NADH oxidation and was abolished by energy inhibitors and by the chromate analog sulfate. The mechanism of resistance to chromate determined by ChrA appears to be based on the active efflux of chromate driven by the membrane potential.

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Li, Ya, Shuang Xi Shao, Lan Jiang, and Kai Qi Shi. "Rare Earth and Tetra Hydroxymethyl Phosphonium Sulfate Combination Tanning." Advanced Materials Research 479-481 (February 2012): 430–33. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.430.

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A new chrome free tanning system of rare earth (RE)-THPS has been developed in this study. It has been proved by UV spectrum that THPS and RE (CeCl3) can coordinate under certain conditions. The influence of CeCl3and THPS’s ratio, pH and ligands on the shrinkage temperature (Ts) was studied. Higher Ts was obtained while the tannage was processed in the sequence of THPS followed by CeCl3. The alkaline pH should be controlled between 5.5 and 6.0 to give ideal tanning effect. It was also found that employing of 0.5% tartaric acid in this combination tanning system can give high Ts of 89°C.

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van Bemmelen, J. M. "Explosion d'un tube contenant des cristaux de sulfate de protoxyde de chrome." Recueil des Travaux Chimiques des Pays-Bas 6, no. 7 (September 6, 2010): 202–4. http://dx.doi.org/10.1002/recl.18870060702.

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Liu, Jianming, Xuyang Yan, Na Liu, Yanyan Zhang, Shufang Zhao, Xiaopei Wang, Kelei Zhuo, and Yuanyuan Yue. "Elemental sulfur accelerated the reactivity of the 3-position of indole for the construction of chromeno[2,3-b]indoles." Organic Chemistry Frontiers 5, no. 6 (2018): 1034–38. http://dx.doi.org/10.1039/c7qo01114h.

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Jarosik, Gregory P., Carol Beth Land, Patrice Duhon, Roderick Chandler, and Tammy Mercer. "Acquisition of Iron by Gardnerella vaginalis." Infection and Immunity 66, no. 10 (October 1, 1998): 5041–47. http://dx.doi.org/10.1128/iai.66.10.5041-5047.1998.

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ABSTRACT Six Gardnerella vaginalis strains were examined for the ability to utilize various iron-containing compounds as iron sources. In a plate bioassay, all six strains acquired iron from ferrous chloride, ferric chloride, ferrous sulfate, ferric ammonium citrate, ferrous ammonium sulfate, bovine and equine hemin, bovine catalase, and equine, bovine, rabbit, and human hemoglobin. All six strains also acquired iron from human lactoferrin, but not from human transferrin, as determined by a liquid broth growth assay. Siderophore production was detected in eight G. vaginalis strains by the chrome azurol S universal chemical assay. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the cytoplasmic membrane proteins isolated from G. vaginalis 594 grown under iron-replete and iron-restricted conditions revealed several iron-regulated proteins ranging in molecular mass from 33 to 94 kDa. These results indicate that G. vaginalis may acquire iron from iron salts and host iron compounds.

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37

Fortes, A. Dominic, Ian G. Wood, and Matthias J. Gutmann. "MgSO4·11H2O and MgCrO4·11H2O based on time-of-flight neutron single-crystal Laue data." Acta Crystallographica Section C Crystal Structure Communications 69, no. 4 (March 12, 2013): 324–29. http://dx.doi.org/10.1107/s0108270113005751.

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Hexaaquamagnesium(II) sulfate pentahydrate, [Mg(H2O)6]SO4·5H2O, and hexaaquamagnesium(II) chromate(II) pentahydrate, [Mg(H2O)6][CrO4]·5H2O, are isomorphous, being composed of hexaaquamagnesium(II) octahedra, [Mg(H2O)6]2+, and sulfate (chromate) tetrahedral oxyanions, SO42−(CrO42−), linked by hydrogen bonds. There are two symmetry-inequivalent centrosymmetric octahedra:M1 at (0, 0, 0) donates hydrogen bonds directly to the tetrahedral oxyanion,T1, at (0.405, 0.320, 0.201), whereas theM2 octahedron at (0, 0, {1 \over 2}) is linked to the oxyanionviafive interstitial water molecules. Substitution of CrVIfor SVIleads to a substantial expansion ofT1, since the Cr—O bond is approximately 12% longer than the S—O bond. This expansion is propagated through the hydrogen-bonded framework to produce a 3.3% increase in unit-cell volume; the greatest part of this chemically induced strain is manifested along theb* direction. The hydrogen bonds in the chromate compound mitigate ∼20% of the expected strain due to the larger oxyanion, becoming shorter (i.e.stronger) and more linear than in the sulfate analogue. The bifurcated hydrogen bond donated by one of the interstitial water molecules is significantly more symmetrical in the chromate analogue.

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38

Chursin, Vyacheslav I., and Alena O. Zaitseva. "SYNTHESIS OF CHROME TANNING AGENT IN PRESENCE OF OLIGO - AND POLYSACCHARIDES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 64, no. 5 (May 14, 2021): 63–70. http://dx.doi.org/10.6060/ivkkt.20216405.6350.

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The conditions for the synthesis of chrome tanning agent during the reduction of sodium dichromate with oligo - and polysaccharides have been investigated. The synthesis of the tanning agent is based on the reduction of hexavalent chromium Cr (VI) in the form of sodium dichromate with reducing agents from the class of vegetable oligo- and polysaccharides with a different sequence of their introduction into the reaction mixture in the presence of sulfuric acid. The introduction of sulfuric acid was carried out gradually to avoid overheating and splashing of the reaction mixture, since the reduction reaction is accompanied by a significant thermal effect. Glucose, maltodextrin and pectin were used as reducing agents. The properties of the obtained products were evaluated by spectrophotometry, conductometry, and analytical methods. It has been shown that the use of native pectin leads to the formation of a gel like mass due to the coordination of the functional groups of galacturonic acid, which is part of the pectin, with chromium atoms. Pretreatment of pectin with a citric acid solution and optimization of synthesis conditions made it possible to obtain a chromium tanning agent that does not contain unreduced chromium. The influence of oligosaccharides on the properties of chromium tanning agents, including their ability to dissolve, is considered. It is shown that the reduction of sodium dichromate with maltodextrin during the reaction results in the formation of incomplete oxidation products of the oligosaccharide, which cause the masking effect of the chromium complex and increase in the resistance of the tanning agent to the action of alkaline reagents used to increase in the basicity during tanning. Experimental samples of chrome tanning agent in dry form were obtained and their leatherprocessing characteristics were studied. The results of technological tests have confirmed the theoretical propositions, according to which the high hydrothermal stability of the leather semifinished product, the almost complete depletion of the processing solution and the required physical and mechanical properties of the finished leather are achieved by introducing the products of incomplete oxidation of oligosaccharides into the inner sphere of the chromium complex.

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Justus, Eugen, Dana T. Izteleuova, Alexander V. Kasantsev, Mendel M. Axartov, Enno Lork, and Detlef Gabel. "Preparation of Carboranyl and Dodecaborate Derivatives of Coumarin." Collection of Czechoslovak Chemical Communications 72, no. 12 (2007): 1740–54. http://dx.doi.org/10.1135/cccc20071740.

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A series of derivatives of coumarin (2H-chromen-2-one) and 6,7-benzocoumarin (3H-benzo-[f]chromen-3-one) carrying the o-carborane, m-carborane, and dodecaborate clusters, has been obtained. X-ray structure analysis has been carried out for three of the products. The addition of o-carborane occurs in the 4-position of the coumarin ring, in a stereoselective way, independent of whether the cluster was reacted as the lithium or magnesium salt. m-Carborane gives two products, one being the result of 1,2-addition to an exocyclic ester bond and 1,4-addition to the coumarin system, the other resulting from 1,4-addition. The negatively charged dodecaborate derivatives obtained, link the cluster via oxygen or sulfur and an appropriate linker to a 7-hydroxy-substituted coumarin. For the coumarin derivatives, an o-carboranecarbonyl derivative could also be obtained.

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Hương, Nguyễn Thị Thanh, Lê Bá Thắng, Lê Đức Bảo, and Đào Bich Thủy. "ATMOSPHERIC CORROSION RESISTANCE OF TRIVALENT AND HEXAVALENT CHROME CONVERSION COATING ON ZINC ELECTRODEPOSITS IN HANOI AFTER 5 YEARS NATURAL EXPOSURE." Vietnam Journal of Science and Technology 56, no. 3B (September 13, 2018): 27. http://dx.doi.org/10.15625/2525-2518/56/3b/12836.

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In this paper, the corrosion resistances obtained after five year exposure of zinc coatings, trivalent chrome conversion coatings (CCCs) and hexavalent CCCs on zinc electroplatings are compared and discussed. The compositions of corrosion products of sample surfaces after exposure are investigated. The results of analysis by means of X-ray diffraction show that the corrosion products formed on zinc coatings, trivalent CCCs, hexavalent CCCs in atmospheric conditions of Hanoi have the distinctions specialty of the humid tropical climates. Zinc sulfate hydroxide hydrate Zn4SO4(OH)6.H2O; Zinc carbonate hydroxide hydrate Zn4CO3(OH)6.H2O; Simonkolleite Zn5(OH)8Cl2.H2O; Chromium Sulfate Cr2(SO4)3; Zinc chloride sulfate hydroxide hydrat Zn12(OH)15(SO4)3Cl3.H2O; Eskolaite Cr2O3 have been identified. The presence of SO2 results in the formation of Zinc sulfate hydroxide hydrate Zn4SO4(OH)6.H2O. After 5 years of exposure in atmospheric conditions, the hexavalent CCCs on zinc coatings have show the best corrosion resistance and the least corrosion products. The corrosion resistance of the samples decreases in the order: 747 > SP25 ~ TM 3108 > Zn.

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Kalnicky, D. J., A. I. Ahonen, M. J. Hietala, and K. J. Kauhanen. "A Compact On-Line XRF Analyzer for Chemical and Petrochemical Processes." Advances in X-ray Analysis 33 (1989): 585–91. http://dx.doi.org/10.1154/s037603080002005x.

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The need for process control has led to the development of improved instrumentation for measuring chemical contents of process streams. In many instances, on-line X-ray Fluorescence (XRF) analysis represents a straightforward method to accomplish these kinds of analyses. The sample preparation is often easy compared to many other methods and the XRF analyzer can be calibrated with process stream or artificial standards. Results are obtained in a time frame suitable for closed-loop control strategies. The Courier 10 is a new, compact on-line XRF analyzer which has been developed for chemical and petrochemical process applications such as sulfur and/or lead in gasoline; calcium in polymers; and chrome, iron ,nickel in metal treatment baths.

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Gillespie, R. J., and R. Kapoor. "The reactions of the chromate, dichromate, and permanganate ions with 100% sulfuric acid and dilute oleum." Canadian Journal of Chemistry 65, no. 11 (November 1, 1987): 2665–69. http://dx.doi.org/10.1139/v87-441.

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Solutions of potassium chromate and potassium dichromate in 100% sulfuric acid and dilute oleum have been investigated by cryoscopic and conductimetric methods. It is shown that they both react to give the compound CrO2(HSO4)2. The absorption spectra of solutions of potassium chromate and dichromate in 100% sulfuric acid are very similar to the spectra of species of the type CrO2X2. Potassium permanganate dissolves in 100% sulfuric acid to give green solutions which are shown to contain MnO3•SO4H. The formation of this compound has been further confirmed by conductimetric measurements in dilute oleum. The absorption spectra of these green solutions are also consistent with the formation of a species of the type MnO3X.

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Sierosławski, Krzysztof, Katarzyna Ślepokura, and Tadeusz Lis. "Potassium (4-methyl-2-oxo-2H-chromen-7-yloxy)sulfate." Acta Crystallographica Section E Structure Reports Online 62, no. 3 (February 22, 2006): m560—m562. http://dx.doi.org/10.1107/s1600536806005137.

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Zhou, Yi Qun, Cheng Gao, Xiao Chao Shi, Jin Yong Xu, and Xun Jiang. "Research on the Preparation of Magnesium Alloy Micro-Arc Oxidation Black Ceramic Membrane." Advanced Materials Research 1030-1032 (September 2014): 165–69. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.165.

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Black ceramic membranes are made on the surface of AZ31B magnesium alloy to further study the micro-arc oxidation coloring ceramic membranes with more colors.In the system of sodium silicate - copper sulfate, black ceramic membrane with good compactness and uniform color can be made while the concentration of sodium silicate is 20g/L and the concentration of copper sulfate is 1.0g/L. Experimental results show that the chroma of the membrane varies from light color system to deep color system with the increasing content of copper aluminum compounds.

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Panswad, Thongchai, Orathai Chavalparit, Yaowanud Sucharittham, and Sasithorn Charoenwisedsin. "A bench-scale study on chromium recovery from tanning wastewater." Water Science and Technology 31, no. 9 (May 1, 1995): 73–81. http://dx.doi.org/10.2166/wst.1995.0346.

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In order to recover chromium, wastewaters from the chrome-tanning process in two Thai tanneries were coagulated with magnesium oxide or sodium carbonate at various dosages. Different types of polymer were also tried to improve the settleability of the chromium sludge which, in turn, was redissolved by sulfuric acid. The produced chromium III sulfate (Cr2(SO4)3) solution was sufficiently concentrated for direct reuse in the tanning step. The settling pattern of the chromium sludge was also observed and optimum sedimentation periods ranging from 1 to 17 hours were suggested. Under no tanning-additive (a chemical to improve chromium sorption onto hides) circumstances, the discharged wastewater contained 5-11 g Cr2O3/l and the most promising coagulant was MgO at a dose of twice the stoichiometric value and an optimum pH of 7-8. The resulting chromium precipitate or sludge was quite dense (21% solids) and possessed a good settling velocity (234 mm/h), making the decantation process very easy, whereas the corresponding acid requirement for the dissolution process was 1.5 times the stoichiometric value. On the other hand, in the tanning-additive situation, the chromium concentration in the drain was reduced to 3-6 g Cr2O3/l. Magnesium oxide was shown to be also the best coagulant but the dose was two times higher than that of the first circumstance, ie., four times that of stoichiometric requirement.

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Evans, David M. "Significance of compositional zoning in cumulate chromites of the Kabanga chonoliths, Tanzania." Mineralogical Magazine 82, no. 3 (May 7, 2018): 675–96. http://dx.doi.org/10.1180/mgm.2018.87.

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ABSTRACTCompositional zoning is observed rarely in chrome-spinel grains from slowly-cooled layered intrusions because diffusion of cations continues within the spinel to low temperatures. However, in certain circumstances, such gradational zoning of both divalent and trivalent cations is observed and may be useful in deciphering the thermal history of the host intrusions. The accessory chrome-spinels of the Kabanga mafic-ultramafic chonolith intrusions of the Kibaran igneous event in north western Tanzania are notable because they have preserved gradational compositional zoning. This zoning is demonstrated to predate and be independent of later hydrous alteration of the silicate assemblage. At Kabanga, most chrome-spinel grains within olivine-rich cumulate rocks are gradationally and cryptically zoned from Fe2+-Cr3+ rich cores to more Mg2+-Al3+ rich rims (normal zoning). A few grains are zoned from Mg2+-Al3+ rich cores to more Fe2+-Cr3+ rich rims (reverse zoned). The zoning of divalent cations is proportional to that of trivalent cations with Mg2+ following Al3+ and Fe2+ following Cr3+ from core to rim. The zoning of trivalent and tetravalent cations is interpreted to be caused by either new growth from an evolving melt or peritectic reactions between evolved or contaminated melt and adjacent Al-Cr-bearing ferromagnesian minerals, which is preserved by relatively rapid initial cooling in the small chonolith intrusions. Divalent cation zoning is controlled by sub-solidus exchange of Fe2+ and Mg with adjacent ferromagnesian minerals and continues to lower temperatures, indicated to be 580 to 630°C by the spinel-olivine geothermometer. Preservation of such zoning is more likely in the smaller chonolith intrusions that typically host magmatic nickel-copper sulfide deposits and can be used as an exploration indicator when interpreting chromite compositions in regional heavy indicator mineral surveys.

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Wünschiers, Röbbe, Thomas Zinn, Dietmar Linder, and Rüdiger Schulz. "Purification and Characterization of Cytochrome c6 from the Unicellular Green Alga Scenedesmus obliquus." Zeitschrift für Naturforschung C 52, no. 11-12 (December 1, 1997): 740–46. http://dx.doi.org/10.1515/znc-1997-11-1204.

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Abstract Purification of a soluble cytochrome c6 from the unicellular green alga Scenedesmus obliquus by a simple and rapid method is described. The purification procedure includes ammonium sulfate precipitation and non-denaturating PAGE. The N-terminal sequence of the first 20 amino acids was determined and shows 85% similarity and 75% identity to the sequence of cytochrome c6 from the green alga Monoraphidium braunii. The ferrocyto-chrome shows typical UV/VIS absorption peaks at 552.9, 521.9 and 415.7 nm. The apparent molecular mass was estimated to be 12 kD a by SDS-PAGE. EPR-spectroscopy at 20K shows resonances indicative for two distinct low-spin heme forms.

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BULBUL, B., P. P. AKALIN, N. BAŞPINAR, M. N. BUCAK, M. KIRBAŞ, C. ÖZTÜRK, S. GÜNGÖR, and K. AKBULUT. "A Comparative Study of Seminal Plasma and Blood Serum Macro and Trace Elements in the the Breeding (October) and the Non-Breeding (April) Seasons in Merino Ram." Journal of the Hellenic Veterinary Medical Society 70, no. 1 (April 24, 2019): 1365. http://dx.doi.org/10.12681/jhvms.20341.

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In this study, it was aimed to investigate the concentrations of macro and trace elements in seminal plasma and blood serum in the breeding (October) and the non-breeding (April) seasons in Merino Ram. Nineteen Merino Rams, aged 18-24 months, were involved in the study. Blood (once) and ejaculate samples (6 replicates) were taken in the breeding (October) and the non-breeding (April) seasons. Blood serum, seminal plasma and diet Calcium, Sodium, Potassium, Magnesium, Phosphorus, Sulfur, Zinc, Selenium, Chrome, Manganese, Nickel, Molybdenum and Boron concentrations were determined by ICP-AES. In blood serum, Sodium and Selenium concentrations were higher (p<0.05 and 0.001, respectively) in the the breeding season than in non-breeding season, whereas Potassium, Chromium and Boron concentrations were lower (p<0.05, 0.001 and 0.001, respectively) in the breeding season than in the non-breeding season. In seminal plasma Calcium, Sodium, Zinc and Manganese concentrations were higher (p<0.05, 0.001, 0.01 and 0.05, respectively) in the breeding season than in the non-breeding season, whereas Phosphorus, Chrome, Molybdenum and Boron concentrations were lower (p<0.001, 0.001, 0.05 and 0.001, respectively) in the breeding season than in the non-breeding season. No difference was detected regarding the other elements. The higher levels of Cr and B in the non-breeding season compared to the breeding season both in serum and seminal plasma, regardless of diet intake, suggest that these elements may play a crutial role on male fertility in Merino Ram.

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Alvarado-Martínez, E., A. M. Costero, S. Gil, and E. Peña-Cabrera. "Sensing and discrimination of cyanide and hydrogen sulfide using an 8-alkenyl-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene derivative." RSC Advances 6, no. 1 (2016): 179–82. http://dx.doi.org/10.1039/c5ra23307k.

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Bansod, Ankur V., Awanikumar P. Patil, and Sourabh Shukla. "Electrochemical evaluation of cr-mn austenitic stainless steel in aqueous sulphuric acid and influence of thiocyanate ions." Anti-Corrosion Methods and Materials 67, no. 3 (April 18, 2020): 281–93. http://dx.doi.org/10.1108/acmm-11-2019-2210.

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Purpose Low nickel austenitic stainless steel (ASS) has attracted much attention worldwide because of its economical price. This study aims to investigate the effect of different corrosive environments on the corrosion behavior of chrome-manganese (Cr-Mn) ASS. The tests were carried out as a function of H2SO4 concentrations, temperature and addition of ammonium thiocyanate (NH4SCN) (0.01 M). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were used to study the corrosion behavior of Cr-Mn ASS. It was observed that with increasing H2SO4 concentration, temperature and with the addition of NH4SCN solution, icorr, icrit and ipassive values increased. EIS data show decreasing charge transfer resistance value with increasing concentration and temperature. Higher corrosion rate with increasing temperature and concentration of H2SO4 is related to the anions (SO42−), which is responsible for reducing the stability of passive films. With the presence of 0.01 M NH4SCN thiocyanate (SCN− anion), there is a higher dilution of the passive film resulting in a higher corrosion rate. Energy-dispersive spectroscopy (EDS) analysis reveals the adsorption of sulfur on the surface in NH4SCN containing a solution. The significant presence of counter ions and the adsorbed sulfur species on the steel surface play a vital role in corrosion behavior. Design/methodology/approach All the experiments were performed on a 3 mm thick sheet of Cr-Mn ASS (202 ASS) in hot rolled condition. The samples were then annealed at 1,050°C for 1 h, followed by water quenching. For microstructural examination, they were electrochemically etched in 10 Wt.% oxalic acid solution at 1 amp for 90 s. A computer-controlled Potentiostat (Biologic VMP-300) was used. After the cell was set up, the working electrode (WE) was electrostatically cleaned at −1 V vs saturated calomel electrode (SCE) for 30 s to remove the air-formed film. Then, WE were allowed to attain stable open circuit potential (OCP) for 1 h, following by the EIS test and potentiodynamic polarization test. The polarization test was started from a cathodic potential (−1.2 V vs SCE) and continued up to an anodic potential (1.6 V vs SCE) a scan rate of 0.1667 mV/s. EIS experiment was conducted on the same instrument by using a sinusoidal AC signal of 10 mV in a frequency range of 1,000,000 to 0.01 Hz at OCP. Findings Potentiodynamic polarization graph shows that with the increase in sulphuric acid concentration. Increasing temperature from 20°C to 80°C in 0.5 M H2SO4 solution increases the corrosion rate (icorr) of Cr-Mn ASS. On the addition of 0.01 M NH4SCN to the sulfuric acid solution (0.1, 0.5 and 1 M) the corrosion rate increases drastically almost four to five times. EDS and XRD analysis shows the presence of sulfur over the oxide film and preferential site for dissolution of Cr and Mn at the steel surface when NH4SCN is added to the sulfuric acid solution. Originality/value A study on the corrosion behavior of Cr-Mn ASS is scanty according to the author’s knowledge. Therefore, the present study will investigate the corrosion behavior of Cr-Mn ASS on SO4−2 anions, temperature and the addition of SCN− ion in sulfuric acid.

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Journal articles on the topic 'Chrome sulfure'

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