159 research outputs found
Deriving formation constants for aqueous metal complexes from XANES spectra: Zn(2+) and Fe(2+) chloride complexes in hypersaline solutions
No full text© 2007 Mineralogical Society of AmericaWeihua Liu, Barbara Etschmann, Garry Foran, Michael Shelley and Joël Brugge
Hydrothermal fluid flow during mineral alteration reactions in geothermal and other systems: An overview
No full textAllan Pring, Barbara Etschmann, Joel Brugger and Yung Nogtha
Transition metals in hypersaline solutions: experiments and numerical modelling
No full textJoël Brugger, Weihua Liu, Barbara Etschmann & Garry Fora
The transformation of pentlandite to violarite under mild hydrothermal conditions: a dissolution-reprecipitation reaction
No full textAllan Pring, Christophe Tenailleau, Barbara Etschmann, Joel Brugger & Ben Grguri
Effect of physical and biogeochemical factors on placer gold transformation in mountainous landscapes of Switzerland
No full textAbstract not availableMaria Angelica D. Rea, Pierre-Alain Wulser, Joël Brugger, Barbara Etschmann, Andrew Bissett, Jeremiah Shuster, Frank Reit
UV-Vis spectrophotometric and XAFS studies of ferric chloride complexes in hyper-saline LiCl solutions at 25-90 degrees C
No full textWeihua Liu, Barbara Etschmann, Joël Brugger, Leone Spiccia, Garry Forane and Brent McInneshttp://www.elsevier.com/wps/find/journaldescription.cws_home/503324/description#descriptio
The oxidation state of europium in hydrothermal scheelite: In situ measurement by xanes spectroscopy
No full textCopyright © 2004 Minerological Association of CanadaJoel Brugger; Barbara Etschmann; Yong S. Chu; Cathy Harland; Stefan Vogt; Chris Ryan; Hugh Jone
An XAS study of the structure and thermodynamics of Cu(I) chloride complexes in brines up to high temperature (400 degrees C, 600 bar)
No full textCopyright © 2007 Elsevier Ltd All rights reserved.J. Brugger, B. Etschmann, W. Liu, D. Testemale, J.L. Hazemann, H. Emerich, W. van Beek and O. Prouxhttp://www.elsevier.com/wps/find/journaldescription.cws_home/212/description#descriptio
Gold particles from Kamchatka: a brief look at gold biogeochemical cycling in a distinct environment
No full textKamchatka is a peninsula located on the far eastern side of Russia and is a geologically active region within the Pacific Ring of Fire. Placer gold particles were obtained from a stream located in the Yelizovsky District and were compared to particles from regions at similar latitudes. Russian gold particle surface textures and morphologies were characterised optically and using electron microscopy, and bacteria occurring on the surface of particles were inferred from detected amplicon sequence variants (ASVs). The gold particles contained remarkably variable gold surface textures with an average 70% of surface area containing clay-filled concavities. Particle morphologies, interpreted from axis ratios, suggested that these particles were transported from primary sources. Proteobacteria constituted 60% of all the detected ASVs from the particles. Within this phylum, Gammaproteobacteria was the most dominant class. This study contributes to the understanding of gold biogeochemical cycling in a distinct bioclimatic environment.Maria Angelica D. Rea, Joël Brugger, Barbara Etschmann, Victor Okrugin and Jeremiah Shuste
Thermodynamic modeling of poorly complexing metals in concentrated electrolyte solutions: an X-ray absorption and UV-Vis spectroscopic study of Ni(II) in the NiCl(2)-MgCl(2)-H(2)O system
No full textKnowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg(-1) NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg(-1) NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system.Ning Zhang, Joël Brugger, Barbara Etschmann, Yung Ngothai, Dewen Zen
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