scholarly journals Removal of trace mercury (II) from aqueous solution by in situ MnOx combined with poly-aluminum chloride

2014 ◽  
Vol 13 (2) ◽  
pp. 383-393 ◽  
Author(s):  
Xixin Lu ◽  
Xiaoliu Huangfu ◽  
Xiang Zhang ◽  
Yaan Wang ◽  
Jun Ma
Keyword(s):  
Water Quality ◽  
Aqueous Solution ◽  
Mercury Concentration ◽  
Aluminum Chloride ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Mercury Removal ◽  
Experimental Conditions ◽  
X Ray

Removal of trace mercury from aqueous solution by Mn (hydr)oxides formed in situ during coagulation with poly-aluminum chloride (PAC) (in situ MnOx combined with PAC) was investigated. The efficiency of trace mercury removal was evaluated under the experimental conditions of reaction time, Mn dosage, pH, and temperature. In addition, the ionic strength and the initial mercury concentration were examined to evaluate trace mercury removal for different water qualities. The results clearly demonstrated that in situ MnOx combined with PAC was effective for trace mercury removal from aqueous solution. A mercury removal ratio of 9.7 μg Hg/mg Mn was obtained at pH 3. Furthermore, at an initial mercury concentration of 30 μg/L and pH levels of both 3 and 5, a Mn dosage of 4 mg/L was able to lower the mercury concentration to meet the standards for drinking water quality at less than 1 μg/L. Analysis by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggests that the hydroxyls on the surface of Mn (hydr)oxides are the active sites for adsorption of trace mercury from aqueous solution.

In Situ X-ray Photoelectron Spectroscopy Detects Multiple Active Sites Involved in the Selective Anaerobic Oxidation of Methane in Copper-Exchanged Zeolites

ACS Catalysis ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 6728-6737 ◽  
Author(s):  
Luca Artiglia ◽  
Vitaly L. Sushkevich ◽  
Dennis Palagin ◽  
Amy J. Knorpp ◽  
Kanak Roy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
X Ray ◽  
Oxidation Of Methane

Role Of Surface Defects In Metal-Ceramic Bonding

1991 ◽  
Vol 238 ◽  
Author(s):  
S. M. Mukhopadhyay ◽  
C. S. Chen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Surface Defects ◽  
Second Phase ◽  
Interfacial Chemistry ◽  
X Ray ◽  
Thin Oxide Film ◽  
Metal Ceramic

ABSTRACTThe interfacial chemistry between Ni and Al2O3 has been studied during the initial stages of bonding. We have evaporated thin films of Ni on different alumina substrates (thin oxide film on metallic Al, polished and scratched sapphire crystals, surface with second phase precipitates) and have analyzed how the interface grows, in situ, using X-ray Photoelectron Spectroscopy. It was found that a certain fraction of the first monolayer of Ni which forms on the alumina surface undergoes charge transfer to form NiO. This is due to oxygen-active sites such as unattached oxygen bonds on the surface. A measure of the concentration of such sites can therefore be obtained from the submonolayer fraction of Ni that gets oxidized. It was found that a rough surface offered less oxidation sites for Ni than a smooth one whereas a surface with second phase MgAI2O4 (spinel) precipitates offered more oxidation sites. Also, there is much less oxidation on a thin film of amorphous alumina grown on metallic Al than on a polished bulk sapphire surface. The implications of these studies to further understanding of the metal-ceramic interface have been discussed.

scholarly journals Acid Red 66 Dye Removal from Aqueous Solution by Fe/C-based Composites: Adsorption, Kinetics and Thermodynamic Studies

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1107 ◽  
Author(s):  
Camila B. Paz ◽  
Rinaldo S. Araújo ◽  
Lais F. Oton ◽  
Alcineia C. Oliveira ◽  
João M. Soares ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Dye Removal ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Carbon Layer ◽  
Synthetic Dyes ◽  
Experimental Conditions ◽  
Paramagnetic Resonance ◽  
X Ray

The presence of synthetic dyes in water causes serious environmental issues owing to the low water quality, toxicity to environment and human carcinogenic effects. Adsorption has emerged as simple and environmental benign processes for wastewater treatment. This work reports the use of porous Fe-based composites as adsorbents for Acid Red 66 dye removal in an aqueous solution. The porous FeC and Fe/FeC solids were prepared by hydrothermal methods using iron sulfates and sucrose as precursors. The physicochemical properties of the solids were evaluated through X-ray diffraction (XRD), Scanning electron microscopy coupled with Energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared s (FTIR), Raman and Mössbauer spectroscopies, nitrogen adsorption–desorption isotherms, Electron Paramagnetic Resonance (EPR) and magnetic saturation techniques. Results indicated that the Fe species holds magnetic properties and formed well dispersed Fe3O4 nanoparticles on a carbon layer in FeC nanocomposite. Adding iron to the previous solid resulted in the formation of γ-Fe2O3 coating on the FeC type structure as in Fe/FeC composite. The highest dye adsorption capacity was 15.5 mg·g−1 for FeC nanocomposite at 25 °C with the isotherms fitting well with the Langmuir model. The removal efficiency of 98.4% was obtained with a pristine Fe sample under similar experimental conditions.

scholarly journals The effect of precursors salts on surface state of Pd/Al2O3 and Pd/CeO2/Al2O3 catalysts

2004 ◽  
Vol 76 (4) ◽  
pp. 825-832 ◽  
Author(s):  
André L. Guimarães ◽  
Lídia C. Dieguez ◽  
Martin Schmal
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Oxygen Storage ◽  
Promoting Effect ◽  
X Ray ◽  
Surface Active ◽  
Al2o3 Catalyst

The influence of the precursors on the promoting effect of ceria on Pd/Al2O3 catalyst, when ceria is coated over alumina was studied. The reaction of propane oxidation proceeded under different feed conditions and the surface active sites were characterized by X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance spectroscopy (DRS). XPS and DRS results show that PdO/Pd0 interface are the active sites independent of the precursor, while the catalysts containing CeO2 showed formation of palladium species in the highest oxidation state, probably PdO2 (338 eV) after the oxidation of propane. Besides, the O/Al and O/Ce ratios evidenced the increase of oxygen storage in the presence of CeO2. In addition, the precursor acetylacetonate favors the oxygen storage in the lattice.

Mechanism of Cu2+ Ions Removal from Aqueous Solution with PBTCA Modified Fe0 Nanoparticles

2014 ◽  
Vol 522-524 ◽  
pp. 454-457
Author(s):  
Jing Wei Feng ◽  
Ying Xia Xu
Keyword(s):  
Aqueous Solution ◽  
Iron Oxide ◽  
Photoelectron Spectroscopy ◽  
Aqueous Media ◽  
Zero Valent Iron ◽  
Borohydride Reduction ◽  
Experimental Conditions ◽  
Redox Mechanism ◽  
X Ray ◽  
Nanoscale Zero Valent Iron

Applications of PBTCA modified nanoscale zero valent iron (P-Fe0) prepared by borohydride reduction for removal of Cu2+ions from aqueous solution are investigated under a variety of experimental conditions. According to X-ray photoelectron spectroscopy (XPS) results, Cu2+ions were removed primarily via a redox mechanism that resulted in the formation of Cu0and Cu2O. The contact of P-Fe0with aqueous media caused extensive formation of iron oxide.

scholarly journals Simultaneous adsorption and reduction of hexavalent chromium on biochar-supported nanoscale zero-valent iron (nZVI) in aqueous solution

2020 ◽  
Vol 82 (7) ◽  
pp. 1339-1349
Author(s):  
Fengfeng Ma ◽  
Bakunzibake Philippe ◽  
Baowei Zhao ◽  
Jingru Diao ◽  
Jian Li
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Photoelectron Spectroscopy ◽  
Zero Valent Iron ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Nanoscale Zero Valent Iron ◽  
Pseudo Second Order

Abstract Flax straw biochar (FSBC)-supported nanoscale zero-valent iron (nZVI) composite (nZVI-FSBC) combining the advantages of nZVI and biochar was synthesized and tested for Cr(VI) removal efficiency from aqueous solution. Surface morphology and structure of FSBC and nZVI-FSBC were characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller techniques, which help to clarify the mechanism of Cr(VI) removal from aqueous solution. The adsorption of Cr(VI) onto FSBC and nZVI-FSBC was best described by the pseudo-second-order and the Sips model. Compared with FSBC, nZVI-FSBC remarkably improved the performance in removing Cr(VI) under identical experimental conditions. Due to the collaborative effect of adsorption and reduction of nZVI-FSBC, the adsorption capacity of nZVI-FSBC for Cr(VI) is up to 186.99 mg/g. The results obtained by XPS, XRD, and FTIR confirmed that adsorption and reduction dominated the processes of Cr(VI) removal by nZVI-FSBC. As a supporter, FSBC not only improved the dispersion of nZVI, but also undertook the adsorption task of Cr(VI) removal. The surface oxygen-containing functional groups of nZVI-FSBC mainly participated in the adsorption part, and the nZVI promoted the Cr(VI) removal through the redox reactions. These observations indicated that the nZVI-FSBC can be considered as potential adsorbents to remove Cr(VI) for environment remediation.

scholarly journals In situ monitoring of the influence of water on DNA radiation damage by near-ambient pressure X-ray photoelectron spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Marc Benjamin Hahn ◽  
Paul M. Dietrich ◽  
Jörg Radnik
Keyword(s):  
Dna Damage ◽  
Radiation Damage ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
In Situ Monitoring ◽  
Strong Increase ◽  
Oh Radicals ◽  
Strand Breaks ◽  
X Ray

AbstractIonizing radiation damage to DNA plays a fundamental role in cancer therapy. X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. The results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further.

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