scholarly journals Recovery of Gold from Ore with Potassium Ferrocyanide Solution under UV Light

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 387
Author(s):  
Ziyuan Liu ◽  
Jue Kou ◽  
Yi Xing ◽  
Chunbao Sun
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Light Response ◽  
Extraction Process ◽  
Potassium Ferrocyanide ◽  
Sensor Surface ◽  
Gold Extraction ◽  
Solution Ph ◽  
Gold Leaching ◽  
Two Stages

In this study, potassium ferrocyanide, a nontoxic cyanide precursor in dark and diffuse reflection environment, was applied as reagent for the leaching of gold. The free cyanide ions could gradually release from potassium ferrocyanide solution under the ultraviolet light. Orthogonal leaching experiments were performed in gold ore to analyze the effect of solution pH, potassium ferrocyanide dosage, and temperature in a potassium ferrocyanide solution system under UV light. Response surface methodology (RSM) was applied to explore the role of potassium ferrocyanide in gold leaching; optimized results showed that the gold recovery reached 67.74% in a high-alkaline environment at a 12.6 pH, 3.8 kg/t potassium ferrocyanide dosage, 62 °C, and irradiance of 10 mW·cm−2. The gold leaching kinetics were monitored by quartz crystal microbalance with dissipation (QCM-D) of potassium ferrocyanide solution. The results indicate that the gold extraction process could be divided into two stages: adsorption and leaching, and a rigid adsorption layer formed on the reaction surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the gold sensor surface after leaching reaction showed that –C≡N appears on the gold sensor surface, and the gold is oxidized to form AuCN complexes.

Preparation and Photocatalytic Properties of La, Ce and Nonmetal N Co-Doped TiO2

2016 ◽  
Vol 680 ◽  
pp. 193-197
Author(s):  
San Ti Yi ◽  
Si Qin Zhao
Keyword(s):  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Uv Light ◽  
Sol Gel ◽  
Light Response ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Co Doped

TiO2, 1%La/TiO2, 1%Ce/TiO2 and a series of Laand Ce co-doped TiO2 photocatalysts were prepared by sol-gel method. Using sol-gel method combine with hydrothermal method prepared rare earth La, Ce and nitrogen co-doped TiO2 photocatalysts. The microstructure, spectroscopy performance and ion doped form of prepared samples were characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy techniques and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of doped TiO2 were examined by measuring the photodegradation of methyl orange. The results showed that the products were all anatase TiO2 nano powder, doping Laor Cehinder the growth of TiO2 particle, further more, doping Laand Cetogether hinder the growth of TiO2 particle more effective, doping N broaden the light response range of TiO2 photocatalyst. At the same time, the photocatalytic activity results indicated that the prepared samples showed superior UV light photocatalytic activity, the sample 1% (La:Ce,9:1)-N/TiO2 showed the highest UV-vis photocatalytic activity.

A novel functionalization of AlGaN/GaN-pH-Sensors for DNA-sensors

2009 ◽  
Vol 1202 ◽  
Author(s):  
Stefanie Linkohr ◽  
S. U. Schwarz ◽  
S. Krischok ◽  
P. Lorenz ◽  
T. Nakamura ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Negative Impact ◽  
Uv Light ◽  
Ph Sensor ◽  
Ph Sensitive ◽  
Dna Sensors ◽  
Sensor Surface ◽  
Photochemical Process ◽  
Pre Treatment ◽  
Illumination Wavelength

AbstractAlGaN/GaN pH sensitive devices were functionalized and passivated for the use as selective bio-sensors. For the passivation, a multilayer of SiO2 and SiNx is proposed, which stabilizes the pH-sensor, is biocompatible and has no negative impact on the following bio-functionalization. The functionalization of the GaN-surface was achieved by covalent bonding of 10-amino-dec-1-ene molecules by a photochemical process. After two different surface preparations islands of TFAAD are growing on the sensor surface by exposure with UV-light. In dependence on the surface pre-treatment and the illumination wavelength the first monolayer is completed after 3 h or 7 h exposure time dependent on the pre-treatment and illumination wavelength. Further exposure results in thicker films as a consequence of cross polymerization. The bonding to the sensor surface was analyzed by X-ray photoelectron spectroscopy, while the thickness of the functionalization was determined by atomic force microscopy scratching experiments. These functionalized devices based on the pH-sensitive AlGaN/GaN ISFET will establish a new family of adaptive, selective biomolecular sensors such as selective, reusable DNA sensors.

Identification of elements hindering gold leaching from gold-bearing dust and selection of gold extraction process

2021 ◽  
pp. 105612
Author(s):  
Pan Cao ◽  
Shuanghua Zhang ◽  
Yajie Zheng ◽  
Shenzhi Lai ◽  
Geyi Liang ◽  
...  
Keyword(s):  
Extraction Process ◽  
Gold Extraction ◽  
Gold Leaching ◽  
Selection Of ◽  
Gold Bearing

scholarly journals Green and Effective Removal of Aqueous Graphene Oxide under UV-Light Irradiation

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 654 ◽  
Author(s):  
Xiaoya Yuan ◽  
Dong Peng ◽  
Qiuye Jing ◽  
Jiawei Niu ◽  
Xin Cheng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Efficiency ◽  
Uv Light ◽  
Light Exposure ◽  
Removal Rate ◽  
Mechanism Study ◽  
Solution Ph ◽  
Transmission Microscopy ◽  
Photogenerated Electrons

The potential extensive application of graphene oxide (GO) in various fields results in the possibility of its release into the natural environment with negative impacts on humans and the ecosystem. The UV-induced removal behavior of aqueous GO was evaluated in this study, and the effect of various parameters (including initial GO concentration, initial solution pH and co-existing ions) on removal rate of GO were investigated in detail. The results showed that UV-light induced a maximum removal rate of GO of 99.1% after 32 h irradiation without any additives, and that the photo-induced removal process in all cases fitted well with pseudo-first-order kinetics. Under optimal conditions, GO was completely removed, with initial GO concentrations of 10 mg/L while adjusting solution pH to 3 or adding Ca2+-containing salt. The GO and photoreduced graphene oxide (prGO) were characterized using High-resolution Transmission Microscopy (HRTEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier-transform Infrared Spectroscopy (FT-IR). The radical species trapping experiments and Electron Spin Resonance (ESR) tests indicated that self-reduction of GO upon UV-light exposure could be achieved via photogenerated electrons from a GO semiconductor. Further mechanism study showed that the high efficiency of UV-induced GO removal came from UV-induced photoreduction, and pH-induced or cation-induced coagulation. This study provided a green and effective method to remove GO from aqueous solutions.

scholarly journals Deposition of Zinc Oxide Coatings on Wood Surfaces Using the Solution Precursor Plasma Spraying Process

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 183
Author(s):  
Ghiath Jnido ◽  
Gisela Ohms ◽  
Wolfgang Viöl
Keyword(s):  
Zinc Oxide ◽  
Ftir Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Color Change ◽  
Uv Light ◽  
Beech Wood ◽  
Nitrate Solution ◽  
Ftir Spectra ◽  
Solution Precursor ◽  
Wood Surfaces

In the present work, the solution precursor plasma spray (SPPS) process was used to deposit zinc oxide (ZnO) coatings on wood surfaces using zinc nitrate solution as precursor to improve the hydrophobicity and the color stability of European beech wood under exposure to ultraviolet (UV) light. The surface morphology and topography of the wood samples and the coatings were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of ZnO was detected with the help of X-ray photoelectron spectroscopy (XPS) and by Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra of the coated samples showed the typical Zn–O band at 445 cm−1. According to the XPS analysis, the coatings consist of two different Zn-containing species: ZnO and Zn(OH)2. Variation of the deposition parameters showed that the most significant parameters affecting the microstructure of the coating were the solution concentration, the deposition scan speed, and carrier gas flow rate. The wettability behaviors of the coated wood were evaluated by measuring the water contact angle (WCA). The coatings that completely covered the wood substrates showed hydrophobic behaviors. UV-protection of wood surfaces after an artificial UV light irradiation was evaluated by color measurements and FTIR spectroscopy. The ZnO-coated wood surfaces were more resistant to color change during UV radiation exposure. The total color change decreased up to 60%. Additionally, the FTIR spectra showed that the wood surfaces coated with ZnO had more stability. The carbonyl groups formation and C=C-bonds consumption were significantly lower.

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.

TiO2 anatase nanotubes for the purification of uranium,arsenic and lead containing water: an X-ray Photoelectron Spectroscopy study

2009 ◽  
Vol 1171 ◽  
Author(s):  
Marco Bonato ◽  
Kristin Vala Ragnarsdottir ◽  
Geoffrey C. Allen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Carbonyl Complexes ◽  
Spectroscopy Study ◽  
High Adsorption ◽  
X Ray ◽  
Tio2 Anatase ◽  
Major Species ◽  
Titania Photocatalyst ◽  
Ph Range

AbstractTiO2 anatase nanotubes synthesised via anodic oxidation were used as adsorbent for the uptake of U and Pb from aqueous solution and the photoremoval of As(III). An X-ray photoelectron spectroscopy study of the sorbent medium surface revealed a high adsorption of U and Pb at pH 8. The adsorption of the uranyl ion was enhanced in an anoxy (N2) atmosphere, because this prevents the formation of very stable carbonyl complexes. As(III) was adsorbed on TiO2 but in the presence of O2 and UV light was oxidized to As(V). XPS analysis revealed that in the pH range 3-9 As(V) was always the major species detected at the surface of the titania photocatalyst.

Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

2021 ◽  
Vol 13 (3) ◽  
pp. 371-380
Author(s):  
Yongjun Wu ◽  
Nina Xie ◽  
Lu Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Formaldehyde Concentration ◽  
Order Kinetic ◽  
Solution Ph ◽  
Visible Absorption ◽  
X Ray ◽  
Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

Analysis of Impact on the Wafer Surface Performance of Supercritical CO2 Extraction

2010 ◽  
Vol 160-162 ◽  
pp. 704-708
Author(s):  
Ru Bing Han
Keyword(s):  
Photoelectron Spectroscopy ◽  
Supercritical Co2 ◽  
Organic Pollution ◽  
Extraction Process ◽  
Surface Cleaning ◽  
Wafer Surface ◽  
Good Prospect ◽  
Supercritical Co2 Extraction ◽  
Extraction Technology ◽  
Surface Performance

The surface of the wafer is easy to be polluted by the organic pollution material. The supercritical fluid extraction technology works well in extracting organic pollution material. Whether the extraction process influences the surface performance of the wafer can be determined through the SEM(scanning electron microscope), AFM (atomic force microscope), and XPS (X-ray photoelectron spectroscopy). Compare the feature and the electronic structure of the wafer before and after supercritical CO2 extraction to get how supercritical CO2 extraction process influences the wafer surface performance. The conclusion helps to determine whether the extraction technology can be applied in the wafer surface cleaning technology. Tests show that supercritical CO2 extraction process almost does not influence the surface performance of the wafer, and, the supercritical CO2 extraction technology has a good prospect in the wafer cleaning.

scholarly journals Influence of Cu(NO3)2 content used in thermal shock method on the photocatalytic activity of Cu-Modified ZnO nanoparticles

2021 ◽  
Vol 5 (3) ◽  
pp. first
Author(s):  
Thế Luân Nguyễn ◽  
Tiến Khoa Lê ◽  
Châu Ngọc Hoàng ◽  
Hữu Khánh Hưng Nguyễn ◽  
Thị Kiều Xuân Huỳnh
Keyword(s):  
Crystal Structure ◽  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Thermal Shock ◽  
Photoelectron Spectroscopy ◽  
Copper Content ◽  
Uv Light ◽  
Copper Nitrate ◽  
X Ray ◽  
Doped Zno

The Cu doped ZnO photocatalysts were prepared on ZnO substrate modified with copper nitrate by thermal shock method with different ratio % molar Cu : Zn = 0.3, 0.5, 1.0, 2.0 and 5.0 in order to study the impacts of copper content on the photocatalytic activity of ZnO under both UV and Vis light irradiation. The crystal structure, morphology bulk and surface were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were studied via time-dependent degradation of methylene blue in aqueous solution. The results exhibit that crystal structure and morphology of Cu doped ZnO photocatalysts is not modified significally than ZnO original but surface charateristicschanged greatly. The photocatalyst was doped with copper content under 2% showed formation of Cu species. These samples perform photocatalytic activity higher than ZnO. The CuNZO-0.05-500 had the highest rate constants for methylene blue degradation (kUV = 6,901 h-1, kVIS = 0,224 h-1), which are about 2.2 times and 1.3 times higher than unmodified ZnO under UV light and Vis light, respectively. However, the CuNZO-5.0-500 which had the formation of CuO phase and unchangeable ZnO's surface has photocatalytic activity similar to pure ZnO.

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