scholarly journals Synchrotron Radiation Based Study of the Catalytic Mechanism of Ag+ to Chalcopyrite Bioleaching by Mesophilic and Thermophilic Cultures

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 382 ◽  
Author(s):  
Zhenyuan Nie ◽  
Weiwei Zhang ◽  
Hongchang Liu ◽  
Jinlan Xia ◽  
Wei Zhu ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Catalytic Mechanism ◽  
Copper Extraction ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
Secondary Minerals ◽  
X Ray ◽  
Catalytic Mechanisms ◽  
X Ray Absorption ◽  
Insight Into

The catalytic mechanism of Ag+ for chalcopyrite bioleaching by mesophilic culture (at 30 °C) and thermophilic culture (at 48 °C) was investigated using synchrotron radiation-based X-ray diffraction (SR-XRD) and S K-edge and Fe L-edge X-ray absorption near edge structure (XANES) spectroscopy. Bioleaching experiments showed that copper extraction from chalcopyrite bioleaching by both cultures was promoted significantly by Ag+, with more serious corrosion occurring on the minerals surface. SR-XRD and XANES analyses showed that the intermediates S0, jarosite and secondary minerals (bornite, chalcocite and covellite) formed for all bioleaching experiments. For these secondary minerals, the formation of bornite and covellite was promoted significantly in the presence of Ag+ for both cultures, while Ag+ has almost no effect on the formation of chalcocite. These results provided insight into the catalytic mechanisms of Ag+ to chalcopyrite bioleaching by the mesophilic and thermophilic cultures, which are both probably due to the rapid formation of bornite by Ag+ and the conversion of bornite to covellite.

Evolution of Leaching Products on the Surface of Chalcopyrite by Mesophiles and Thermophiles Based on SR-XRD and XANES Spectroscopy

2015 ◽  
Vol 1130 ◽  
pp. 282-286 ◽  
Author(s):  
Hong Chang Liu ◽  
Jin Lan Xia ◽  
Zhen Yuan Nie ◽  
Hong Rui Zhu ◽  
Yi Dong Zhao ◽  
...  
Keyword(s):  
Mixed Cultures ◽  
Xanes Spectroscopy ◽  
Copper Extraction ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Leaching Solution ◽  
Moderate Thermophiles ◽  
Sulfur Oxidizing ◽  
X Ray Absorption

The bioleaching experiments of chalcopyrite were conducted with single and mixed mesophiles (30 °C) and moderate thermophiles (45 °C) and extreme thermophile (65 °C), respectively, and analyzed by synchrotron radiation (SR) based X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the copper extraction of chalcopyrite could be significantly promoted by bioleaching microorganisms, and the promotion effects for both the mixed cultures grown at different temperature and the different cells grown at the same temperature were significantly different. The surface of chalcopyrite after bioleached by the mixed or sole cultures are serious corroded and became complicated. More S0 was found to form in the sole cultures of specific iron-oxidizing microorganism L. ferrooxidans and L. ferriphilum and sulfur-oxidizing microorganisms A. thiooxidans and A. caldus cultures. Jarosite and secondary minerals (chalcocite and covellite) were detected for the mixed cultures and sole cultures of iron/sulfur-oxidizing microorganisms. The evolution of chalcocite and covellite were just relevant to the potential of leaching solution, no matter which cultures were used, where chalcocite could be formed at Eh value less than 500 mV and then converted to covellite at Eh value ~550 mV.

Material Characteristics and Electrical Modeling of Ultra Thin Copper Oxides in ULSI Application

2007 ◽  
Vol 561-565 ◽  
pp. 1225-1228
Author(s):  
Takayuki Ohba
Keyword(s):  
Diffraction Pattern ◽  
Barrier Height ◽  
Oxide Thickness ◽  
Amorphous Structure ◽  
Emission Model ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Current Emission ◽  
X Ray Absorption

With the highest brilliance synchrotron radiation X-ray (SPring-8) and TEM observations, Cu oxides ranged 2-nm to 10-nm in thickness formed on sputtered Cu has been evaluated. For the plasma-assisted Cu oxide, weak Cu2O and/or CuO X-ray diffraction pattern is observed, while no diffraction pattern in native and thermally (170°C) grown oxides. Those native and thermal oxides show Cu2O coordination observed by XANES (X-ray Absorption Near Edge Structure) method. This suggests that Cu oxide formed at low temperatures consists of stoichiometric Cu2O in an amorphous structure. According to the Fowler-Nordheim (F-N) current emission model, the current emission taking place at Cu2O decreases with increasing of the oxide thickness and its mean barrier height (φB) in the MIM band structure. In case of current density at 106A/cm2 of 1V, it is estimated that the allowable thickness of Cu oxides is approximately 1.5-nm at 1 eV of barrier height.

scholarly journals The Atomic-Scale Interaction of Bioactive Glasses with Simulated Body Fluid

2005 ◽  
Vol 480-481 ◽  
pp. 21-26 ◽  
Author(s):  
L.J. Skipper ◽  
F.E. Sowrey ◽  
D.M. Pickup ◽  
R.J. Newport ◽  
K.O. Drake ◽  
...  
Keyword(s):  
Simulated Body Fluid ◽  
Body Fluid ◽  
Sol Gel ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Bioactive Glasses ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

The formation of a carbonate-containing hydroxyapatite, HCAp, layer on bioactive calcium silicate sol-gel glass of the formula (CaO)0.3(SiO2)0.7 has been studied in-vitro in Simulated Body Fluid (SBF). Extended X-ray Absorption Fine Structure (EXAFS), X-ray Absorption Near Edge Structure (XANES), X-ray diffraction (XRD), and solid state nuclear magnetic resonance (NMR) measurements have been performed with results showing the formation of a significantly amorphous HCAp layer after less than 5 hours in solution.

Eyeing the past: synchrotron µ-XANES and XRF imaging of tarnish distribution on 19th century daguerreotypes

2019 ◽  
Vol 26 (5) ◽  
pp. 1679-1686 ◽  
Author(s):  
M. S. Kozachuk ◽  
T. K. Sham ◽  
R. R. Martin ◽  
A. J. Nelson ◽  
I. Coulthard
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Synchrotron Radiation ◽  
National Gallery ◽  
Edge Structure ◽  
X Ray ◽  
The Past ◽  
National Gallery Of Canada ◽  
X Ray Absorption ◽  
Scanning Electron

Louis-Jacques-Mandé Daguerre introduced the first successful photographic process, the daguerreotype, in 1839. Tarnished regions on daguerreotypes supplied by the National Gallery of Canada were examined using scanning electron microscopy energy-dispersive X-ray spectroscopy and synchrotron-radiation analysis. Synchrotron X-ray fluorescence imaging visualized the distribution of sulfur and chlorine, two primary tarnish contributors, and showed that they were associated with the distribution of image particles on the surface. X-ray absorption near-edge structure spectroscopy determined the tarnish to be primarily composed of AgCl and Ag2S. Au2S, Au2SO4, HAuCl4 and HgSO4 were also observed to be minor contributors. Environmental contamination may be a source of these degradation compounds. Implications of these findings will be discussed.

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