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Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains BJM
Madrigal-Arias,Jorge Enrique; Argumedo-Delira,Rosalba; Alarcón,Alejandro; Mendoza-López,Ma. Remedios; García-Barradas,Oscar; Cruz-Sánchez,Jesús Samuel; Ferrera-Cerrato,Ronald; Jiménez-Fernández,Maribel.
In an effort to develop alternate techniques to recover metals from waste electrical and electronic equipment (WEEE), this research evaluated the bioleaching efficiency of gold (Au), copper (Cu) and nickel (Ni) by two strains of Aspergillus niger in the presence of gold-plated finger integrated circuits found in computer motherboards (GFICMs) and cellular phone printed circuit boards (PCBs). These three metals were analyzed for their commercial value and their diverse applications in the industry. Au-bioleaching ranged from 42 to 1% for Aspergillus niger strain MXPE6; with the combination of Aspergillus niger MXPE6 + Aspergillus niger MX7, the Au-bioleaching was 87 and 28% for PCBs and GFICMs, respectively. In contrast, the bioleaching of Cu by Aspergillus...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Bioleaching; PCBs; Aspergillus; Gold; WEEE.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822015000300707
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Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil Anais da ABC (AABC)
Mexias,André S.; Berger,Gilles; Gomes,Márcia E.B.; Formoso,Milton L.L.; Dani,Norberto; Frantz,José C.; Bongiolo,Everton M..
A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package using conditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco do Butiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold). The pyrite occurs associated with white mica (phengite) in the zone of phyllic alteration. The process of gold deposition showed to be related to temperature and pH decrease. The pH decrease was fundamental to gold deposition by destabilization of sulfur species [Au(HS)2- , HAu(HS)2(0) and Au(HS)0] dissolved in the aqueous solution, being Au(HS)0 the main gold transporting complex. The addition of KCl is hard to accept as cause of gold precipitation...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Geochemical modeling; Gold; Pyrite; Sulfur; Fluid-rock interaction.
Ano: 2005 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652005000400010
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Immobilization of Protein A on SAMS for the elaboration of immunosensors ArchiMer
Briand, Elisabeth; Salmain, Michèle; Compere, Chantal; Pradier, Claire-marie.
Binary mixtures of 11-mercaptoundecanoic acid (MUA) and other thiols of various lengths and terminal functions were chemisorbed on gold-coated surfaces via S-Au bonds to form mixed self-assembled monolayers (SAMs). Several values of the inole fraction of MUA in the thiol mixtures were tested and the structure and composition of the resulted thin films were characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The results made it clear that co-adsorption of MUA with thiols of similar chain length led to well-ordered monolayers whereas the co-adsorption of MUA with shorter thiols yielded less crystalline-like thin films, but with more reactive carboxylic acid terminal...
Tipo: Text Palavras-chave: PM IRRAS; Antibody; Protein A; Gold; Self assembled monolayers.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-2222.pdf
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Sulfide determination in hydrothermal seawater samples using a vibrating gold micro-wire electrode in conjunction with stripping chronopotentiometry ArchiMer
Aumond, Virginie; Waeles, Mathieu; Salaun, Pascal; Gibbon-walsh, Kristoff; Van Den Berg, Constant M. G.; Sarradin, Pierre-marie; Riso, Ricardo D..
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at -0.25 V (vs Ag/AgCl, KCl 3 M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically -2 mu A). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30 nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ....
Tipo: Text Palavras-chave: Sulfide; Stripping chronopotentiometry; Vibrating electrode; Gold; Seawater; Hydrothermal.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00111/22222/20065.pdf
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THE DISTRIBUTIONAL BEHAVIOR OF FUTURES PRICE SPREADS AgEcon
Kim, MinKyoung; Leuthold, Raymond M..
The distributional behavior of futures price spreads is examined for four commodities: corn, live cattle, gold and T-bonds. Remarkably different results are found over commodities, time period, and sample size. Actual spread changes for the smaller sample size of gold and T-bonds and for corn produce more normal distributions for weekly than for daily differencing intervals, while all live cattle spreads for actual changes are normally distributed. However, the larger sample size of both gold and T-bonds and the relative spread changes for corn and live cattle do not become more normally distributed under temporal aggregation of the data.
Tipo: Journal Article Palavras-chave: Corn; Futures price spreads; Gold; Goodness of fit; Live cattle; Normality tests; Spread distributions; T-bonds; Marketing.
Ano: 2000 URL: http://purl.umn.edu/15399
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