scholarly journals Dissolution and Passivation of Chalcopyrite during Bioleaching by Acidithiobacillus ferrivorans at Low Temperature

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 332 ◽  
Author(s):  
Tangjian Peng ◽  
Lei Chen ◽  
Jingshu Wang ◽  
Jie Miao ◽  
Li Shen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Sulfur Oxidation ◽  
Quantitative Real Time Pcr ◽  
Mineral Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Opposite Trend ◽  
Iron And Sulfur Oxidation ◽  
Scanning Electron

Our knowledge on the dissolution and passivation mechanisms of chalcopyrite during bioleaching at low temperature has been limited to date. In this study, an Acidithiobacillus ferrivorans strain with high tolerance to heavy metals and UV radiation was used for chalcopyrite bioleaching. At 6 °C, no apparent precipitate was detected on the mineral surface after bioleaching using a scanning electron microscope (SEM). X-ray diffraction (XRD) revealed that the ore residue contained only chalcopyrite and quartz. X-ray photoelectron spectroscopy (XPS) analysis revealed that the content of S0 on the mineral surface remained low and the ratio of SO42− decreased from 46.7% to 20.9%, but the amount of Sn2− increased from 10.4% to 21.4% after bioleaching. Expression of five critical iron- and sulfur-oxidation genes during bioleaching was analyzed using quantitative real-time PCR. The gene rusA had higher expression in the mid-log phase than in the stationary phase but hdrA and cyoC1 showed an opposite trend. All genes had higher expression at 6 °C than at 28 °C, so as to compensate for the decline in the enzyme activities. The study revealed that polysulfide was the most plausible passivating substance at 6 °C, and the strain can maintain the iron- and sulfur-oxidation activities during low-temperature bioleaching.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Synthesis and characterization of homogeneous lead-substituted tin oxide with the (110) face of rutile structure

2000 ◽  
Vol 15 (10) ◽  
pp. 2076-2079
Author(s):  
Chika Nozaki ◽  
Takashi Yamada ◽  
Kenji Tabata ◽  
Eiji Suzuki
Keyword(s):  
Electron Microscopy ◽  
Tin Oxide ◽  
Photoelectron Spectroscopy ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Rutile Structure ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Synthesis of a rutile-type lead-substituted tin oxide with (110) face was investigated. The characterization was performed by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface area measurements. The homogeneous rutile-type lead-substituted tin oxide was obtained until 4.1 mol% of tin was substituted with lead. The surface of obtained oxide had a homogeneously lead-substituted (110) face.

Magnesium Nitrate as Additive for Synthesis of Mg(OH)2 Nanoparticles

2012 ◽  
Vol 198-199 ◽  
pp. 99-102
Author(s):  
Qing Gang Kong ◽  
Hai Yan Qian
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Magnesium Nitrate ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size And Morphology ◽  
Scanning Electron

Magnesium nitrate was used as additive for synthesis of Mg(OH)2 (MH) nanoparticles at low temperature (70°C). Mg(OH)2 nanoparticles have platelet-like structure and approximately 40-60nm in thicknesses. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to characterize the crystal phase. The supersaturation degree of solution effects the size and morphology of MH nanoparticles.

scholarly journals Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Long Lu ◽  
Xueman Wang ◽  
Chunhua Hu ◽  
Ying Liu ◽  
Xiongbo Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Redox Capacity ◽  
Scr Of No ◽  
Temperature Programmed

Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

scholarly journals Reduced Graphene Oxide–Epoxy Grafted Poly(Styrene-Co-Acrylate) Composites for Corrosion Protection of Mild Steel

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 666
Author(s):  
Xinchuan Fan ◽  
Yue Hu ◽  
Yijun Zhang ◽  
Jiachen Lu ◽  
Xiaofeng Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Scanning Electron

Reduced graphene oxide–epoxy grafted poly(styrene-co-acrylate) composites (GESA) were prepared by anchoring different amount of epoxy modified poly(styrene-co-acrylate) (EPSA) onto reduced graphene oxide (rGO) sheets through π–π electrostatic attraction. The GESA composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The anti-corrosion properties of rGO/EPSA composites were evaluated by electro-chemical impedance spectroscopy (EIS) in hydroxyl-polyacrylate coating, and the results revealed that the corrosion rate was decreased from 3.509 × 10−1 to 1.394 × 10−6 mm/a.

Effect of Cu Content on the Tribological Performance of Cr-N Coatings at High Temperatures (840°C)

2009 ◽  
Author(s):  
Kyriaki Polychronopoulou ◽  
Claus Rebholz ◽  
Nicholaos G. Demas ◽  
Andreas A. Polycarpou ◽  
P. N. Gibson
Keyword(s):  
Vapor Deposition ◽  
Photoelectron Spectroscopy ◽  
Physical Vapor Deposition ◽  
Tribological Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Content ◽  
Glancing Angle ◽  
Scanning Electron ◽  
Ball On Disc

Cr-N and Cu-Cr-N coatings with Cu content between 3–65 at.%, Cu/Cr ratios in the 0.04–4.5 range and 21–27 at.% N, synthesized by twin e-beam Physical Vapor Deposition (EBPVD) at 450°C, were investigated. Using X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (GAXRD) and scanning electron microscopy (SEM), in combination with nanoindentation mechanical property measurements and laboratory controlled ball-on-disc sliding experiments, it is shown that Cu-Cr-N coatings with low Cu content (3 at.%) possess sufficient wear resistance for high temperature demanding tribological applications.

scholarly journals Preparation of Cerium Dioxide Layers on Titanium by Electrodeposition with Organic Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Vaijayanti Namdeo Nande ◽  
Diana Kostyukova ◽  
Jeonghee Choi ◽  
Yong Hee Chung
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Cerium Dioxide ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Organic Solution ◽  
X Ray ◽  
Titanium Foils ◽  
Scanning Electron

Layers of cerium dioxide nanoparticles were prepared on titanium by electrodeposition with organic solution. Three concentrations of cerium ions were used at 31.6 V. The organic solution was isobutanol and titanium foils were used as anodes and cathodes. Currents were monitored during the electrodeposition. Deposition times ranged from 0.5 to 8 h. Deposited Deposited layers were calcined at 700 K for 30 min. The morphology and composition of the deposited layers were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). As-prepared and calcined deposition layers were assayed to be cerium dioxide. The average crystallite size increased from 4 to 7 nm through calcination at 700 K. Sizes of calcined cerium oxide agglomerates were ranging from 73 to 146 nm for 30 min deposition and 209 to 262 nm for 8 h deposition. The electrodeposition efficiencies of 0.5 h deposition at three concentrations were measured to be highest.

SiO2ZrO2 Thin Films as Low Temperature NO2 and O3 Sensors

2015 ◽  
Vol 1088 ◽  
pp. 81-85 ◽  
Author(s):  
T.N. Myasoedova ◽  
Victor V. Petrov ◽  
Nina K. Plugotarenko ◽  
Dmitriy V. Sergeenko ◽  
Galina Yalovega ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Operating Temperatures ◽  
Scanning Electron

Thin SiO2ZrO2films were prepared, up to 0.2 μm thick, by means of the sol–gel technology and characterized by a Scanning electron microscopy and X-ray diffraction. It is shown the presence of monoclinic, cubic and tetragonal phases of ZrO2in the SiO2matrix. The crystallites sizes depend on the annealing temperature of the film and amount to 35 and 56 nm for the films annealed at 773 and 973 K, respectively. The films resistance is rather sensitive to the presence of NO2and O3impurity in air at lower operating temperatures in the range of 30-60°C.

Photoelectrocatalytic Degradation of HCB by N-Doped TiO2 Nanotube Arrays

2013 ◽  
Vol 652-654 ◽  
pp. 1580-1584
Author(s):  
Yu Jiang Guan ◽  
Zi Bo Wang ◽  
Shu Li Bai ◽  
Qin Xue
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Nanotube Arrays ◽  
Simulated Sunlight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photoelectrocatalytic Degradation ◽  
Doping Behavior ◽  
Doped Titanium Dioxide ◽  
Scanning Electron

N-doped Titanium dioxide (TiO2) nanotube arrays were characterized by scanning electron microscope (SEM)，X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to analyse its surface morphology, crystal types and the doping behavior of nitrogen. The material was used as electrode for photoelectrocatalytic degradation of hexachlorobenzen under irradiation of simulated sunlight. The effects of photocatalysis, electrocatalysis, photoelectrocatalysis, the concentration of Na2SO4 and pH value on degradation of HCB were investigated.

Preparation and Characterization of N Doped TiO2/ Sepiolite Composite Materials

2011 ◽  
Vol 284-286 ◽  
pp. 597-600
Author(s):  
Dai Mei Chen ◽  
Hai Peng Ji ◽  
Jian Xin Wang ◽  
Jian Chen ◽  
Xin Long Luan ◽  
...  
Keyword(s):  
Composite Materials ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nitrogen Doped ◽  
Nitrogen Contents ◽  
Scanning Electron ◽  
Oxygen Atoms

Nitrogen doped TiO2/sepiolite composite materials (N-TiO2/sep) with different nitrogen contents were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), respectively. XRD and SEM results showed that anatase-TiO2nanoparticles were distributed homogenously on the surface of sepiolite. XPS revealed that N atoms could incorporate into the lattice of anatase TiO2substituting the oxygen atoms sites of oxygen atoms.

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