In situ remediation of arsenic-rich mine tailings using slag zero valence iron

2020 ◽  
Vol 84 (3) ◽  
pp. 420-434
Author(s):  
Tingting Yue ◽  
Shu Chen ◽  
Jing Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Solid Phase ◽  
Low Cost ◽  
Selective Extraction ◽  
Hunan Province ◽  
Control Group ◽  
X Ray Diffraction ◽  
Land Occupation ◽  
X Ray

AbstractArsenopyrite (FeAsS) and realgar (As4S4) are two common arsenic minerals that often cause serious environmental issues. Centralised treatment of arsenic-containing tailings can reduce land occupation and save management costs. The current work examined the remediation schemes of tailings from Hunan Province, China, where by different tailings containing arsenopyrite and realgar were blended with exogenous slag zero valence iron (ZVI). Introducing Fe-oxidising bacteria (Acidithiobacillus ferrooxidans) recreates a biologically oxidative environment. All bioleaching experiments were done over three stages, each for 7 days and the solid phase of all tests was characterised by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and selective extraction analyses. The results showed that the mixture group reduced arsenic release by 72.9–74.7% compared with the control group. The addition of 0.2 g ZVI clearly decreased arsenic release, and the addition of 4.0 g ZVI led to the lowest arsenic release among all tests. The decrease of arsenic released from the tailings was due to the adsorption and uptake of arsenic by secondary iron-containing minerals and Fe–As(V) secondary mineralisation. The addition of large amounts of ZVI reduced the arsenic detected in the amorphous Fe precipitates. Therefore, a low cost and integrated strategy to reduce arsenic release from tailings is to mix two typical tailings and apply exogenous slag ZVI, which can apply to the in situ remediation of two kinds or more arsenic-containing tailings.

Nanocomposite cellulose fabrics with in situ generated silver nanoparticles by bioreduction method

2020 ◽  
pp. 152808372092473 ◽  
Author(s):  
Suchart Siengchin ◽  
Pawinee Boonyasopon ◽  
Vajja Sadanand ◽  
Anumakonda Varada Rajulu
Keyword(s):  
Silver Nanoparticles ◽  
Size Range ◽  
Low Cost ◽  
Aqueous Dispersion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gram Positive Bacteria ◽  
Bed Materials ◽  
Cellulose Fabrics

In the present work, nanocomposite cellulose fabrics with in situ generated silver nanoparticles were prepared by bioreduction method employing aqueous dispersion of low-cost natural turmeric powder as a reducing agent and different concentrated aqueous AgNO3 as source solutions. The prepared nanocomposite cellulose fabrics were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and antibacterial tests. The nanocomposite cellulose fabrics had roughly spherical silver nanoparticles in the size range of 41–130 nm with an overall average of 78 nm. The X-ray analysis indicated the generation of both silver nanoparticles and Ag2O nanoparticles in the nanocomposite cellulose fabrics. The nanocomposite cellulose fabrics retained the generated AgNPs even after repeated detergent washings. The prepared nanocomposite cellulose fabrics exhibited excellent antibacterial activity against both the Gram-negative and Gram-positive bacteria and hence can be considered as antibacterial hospital-bed materials, apparels, etc.

scholarly journals Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

2019 ◽  
Vol 9 (4) ◽  
pp. 793 ◽  
Author(s):  
Camila Zequine ◽  
Fangzhou Wang ◽  
Xianglin Li ◽  
Deepa Guragain ◽  
S.R. Mishra ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Nickel Foam ◽  
Low Cost ◽  
Agricultural Waste ◽  
Bifunctional Catalyst ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electroactive Material

The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost.

An Efficient Simple Hydrothermal Method to Synthesis FeS2 Microspheres and their Optical Property

2016 ◽  
Vol 847 ◽  
pp. 72-77
Author(s):  
Yu Xuan Liang ◽  
Peng Peng Bai ◽  
Shu Qi Zheng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Wave Length ◽  
Functional Materials ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Synthetic Sample ◽  
X Ray ◽  
New Type ◽  
Good Uniformity

Pyrite (FeS2) is an important semiconductor material which shows various excellent optical and electrical properties and extensive applied prospect as a new-type, photoelectrical functional materials. In this study, a low cost and efficient simple hydrothermal two-step synthetic method was given to obtain FeS2 microspheres with 2-3 μm in diameter. The obtained products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet and visible spectrophotometer (UV-Vis). XRD showed that the synthetic sample consisted of two crystal structures of FeS2, pyrite and marcasite. SEM observation indicated that FeS2 microspheres were well crystallized and had good uniformity. UV-Vis spectrum had a strong optical absorption in the region of 200-400 nm wave length. The reaction temperature had an impact on the size of FeS2 microspheres. A possible mechanism for the size of the FeS2 microspheres generated at high temperature is smaller than that at low temperature is discussed.

scholarly journals “PdO vs. PtO”—The Influence of PGM Oxide Promotion of Co3O4 Spinel on Direct NO Decomposition Activity

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 62 ◽  
Author(s):  
Gunugunuri K. Reddy ◽  
Torin C. Peck ◽  
Charles A. Roberts
Keyword(s):  
Photoelectron Spectroscopy ◽  
No Decomposition ◽  
Single Element ◽  
X Ray Diffraction ◽  
X Ray ◽  
Promotional Effect ◽  
Ft Ir ◽  
Temperature Programmed ◽  
Thermal Stability Of

Direct decomposition of NO into N2 and O2 (2NO→N2 + O2) is recognized as the “ideal” reaction for NOx removal because it needs no reductant. It was reported that the spinel Co3O4 is one of the most active single-element oxide catalysts for NO decomposition at higher reaction temperatures, however, activity remains low below 650 °C. The present study aims to investigate new promoters for Co3O4, specifically PdO vs. PtO. Interestingly, the PdO promoter effect on Co3O4 was much greater than the PtO effect, yielding a 4 times higher activity for direct NO decomposition at 650 °C. Also, Co3O4 catalysts with the PdO promoter exhibit higher selectivity to N2 compared to PtO/Co3O4 catalysts. Several characterization measurements, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR), and in situ FT-IR, were performed to understand the effect of PdO vs. PtO on the properties of Co3O4. Structural and surface analysis measurements show that impregnation of PdO on Co3O4 leads to a greater ease of reduction of the catalysts and an increased thermal stability of surface adsorbed NOx species, which contribute to promotion of direct NO decomposition activity. In contrast, rather than remaining solely as a surface species, PtO enters the Co3O4 structure, and it promotes neither redox properties nor NO adsorption properties of Co3O4, resulting in a diminished promotional effect compared to PdO.

Structural Characterization of Ion Beam Enhanced Solid Phase Epitaxial Regrowth by Raman, RBS, and X-Ray Analysis

1988 ◽  
Vol 126 ◽  
Author(s):  
John F. Knudsen ◽  
R. C. Bowman ◽  
P. M. Adams ◽  
R. Newman ◽  
J. P. Hurrell ◽  
...  
Keyword(s):  
Solid Phase ◽  
Ion Beam ◽  
Beam Current ◽  
Crystalline Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Epitaxial Regrowth ◽  
High Beam Current

ABSTRACTEpitaxial regrowth of deposited amorphous silicon has been previously described utilizing ion implantation amorphization, ion mixing and thermal anneal. This paper evaluates the effects of these process steps on crystalline quality utilizing Rutherford Backscattering (RBS), x-ray diffraction rocking curves and Raman scattering.In situ (during implantation) regrowth results in defective crystallinity. In contrast, when there is no in situ regrowth, the post anneal crystallinity is equivalent by RBS and x-ray evaluation to virgin single crystal wafers. In situ regrowth is most pronounced during the high beam current ion mixing type implants which produce wafer temperatures of about 250°C. The final crystalline quality which results from different sequences of amorphization and ion mixing implants, is strongly dependent upon the amount of in situ regrowth which has occurred. The greater the in situ regrowth the poorer the final crystalline quality.

A dispenser–reactor apparatus applied forin situXAS monitoring of Pt nanoparticle formation

2015 ◽  
Vol 22 (3) ◽  
pp. 736-744 ◽  
Author(s):  
Jocenir Boita ◽  
Marcus Vinicius Castegnaro ◽  
Maria do Carmo Martins Alves ◽  
Jonder Morais
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metallic Nanoparticles ◽  
Pt Nanoparticles ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Two Stages ◽  
X Ray Absorption

In situtime-resolved X-ray absorption spectroscopy (XAS) measurements collected at the PtL3-edge during the synthesis of Pt nanoparticles (NPs) in aqueous solution are reported. A specially designed dispenser–reactor apparatus allowed for monitoring changes in the XAS spectra from the earliest moments of Pt ions in solution until the formation of metallic nanoparticles with a mean diameter of 4.9 ± 1.1 nm. By monitoring the changes in the local chemical environment of the Pt atoms in real time, it was possible to observe that the NPs formation kinetics involved two stages: a reduction-nucleation burst followed by a slow growth and stabilization of NPs. Subsequently, the synthesized Pt NPs were supported on activated carbon and characterized by synchrotron-radiation-excited X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS). The supported Pt NPs remained in the metallic chemical state and with a reduced size, presenting slight lattice parameter contraction in comparison with the bulk Pt values.

Low Cost Integrated Sensors Utilizing Patterned Nano-Structured Titania Arrays Fabricated Using a Simple Process

2004 ◽  
Vol 828 ◽  
Author(s):  
Zuruzi Abu Samah ◽  
Andrei Kolmakov ◽  
Martin Moskovits ◽  
Noel C. MacDonald
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Aqueous Hydrogen Peroxide ◽  
X Ray ◽  
Sensing Systems ◽  
Potential Applications ◽  
Nano Wires ◽  
Low Temperature Process

ABSTRACTUsing a novel low-temperature process, we demonstrate the facile integration of crack-free nanostructured titania (NST) as sensing elements in microsystems. Unlike conventional sol-gel methods, NST layers of interconnected nano-walls and nano-wires were formed by reacting Ti surfaces with aqueous hydrogen peroxide solution. Cracks were observed in NST layers formed on blanket Ti films but absent on arrays of patterned Ti pads below a threshold dimension. Analyses using TEM, high resolution SEM, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) reveal that NST consists of anatase TiO2 nano-crystals. NST pads were found able to detect oxygen gas of a few ppm. NST pad arrays were integrated on rigid and flexible substrates with potential applications in low cost and wearable sensing systems.

Surface nitridation of Ta powder by molten-salt electrolysis of Ta2O5 under N2 atmosphere

2020 ◽  
Vol 13 (07) ◽  
pp. 2050032
Author(s):  
Qing Huang ◽  
Guojin Zheng ◽  
Tian Wu
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Cell Voltage ◽  
X Ray Diffraction ◽  
Molten Salt Electrolysis ◽  
X Ray ◽  
Structured Catalysts ◽  
Transmission Electron ◽  
N2 Atmosphere

The electro-deoxidation of Ta2O5 in molten CaCl2 under N2 atmosphere is a facile way for the in situ surface nitridation of Ta particles. The cell voltage and electrolysis time of Ta2O5 are rationalized to realize the in situ surface nitridation of Ta. All the characterization results including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elements mapping as well as X-ray photoelectron spectroscopy (XPS) confirm the formation of Ta2N layers on the surface of Ta particles, with the thickness of 3–4[Formula: see text]nm. This method provides a strategy for the facile in situ surface nitridation with N2 as the nitrogen source for the fabrication of core-shell structured catalysts.

Effect of HCl+LiF Etching Process on Electrochemical Performance of Ti3C2

NANO ◽  
2020 ◽  
Vol 15 (05) ◽  
pp. 2050058
Author(s):  
Yuhua Huang ◽  
Weiwei Li ◽  
Bingchu Mei ◽  
Yu Yang ◽  
Zuodong Liu
Keyword(s):  
Electrochemical Performance ◽  
Photoelectron Spectroscopy ◽  
Lithium Fluoride ◽  
Specific Capacity ◽  
Etching Process ◽  
X Ray Diffraction ◽  
In Situ Oxidation ◽  
X Ray ◽  
Scanning Electron

In this paper, the effects of etching temperature and concentrations of hydrochloric acid (HCl) on the exfoliating process and the electrochemical performance of LIBs were systematically explored. The transformation from Ti3AlC2 to Ti3C2 was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectra. The suitable conditions of preparing Ti3C2 MXene though HCl and lithium fluoride (LiF) were obtained. Besides, the in-situ oxidation conditions of Ti3C2 during the etching process were studied. The TiO2/Ti3C2 was beneficial to improve the specific capacity from 125[Formula: see text]mAh[Formula: see text]g[Formula: see text] to 150[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 1 C.

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