Kinetics and mechanism of Mn2+ removal from groundwater using iron–manganese co-oxide filter film

2019 ◽  
Vol 19 (6) ◽  
pp. 1711-1717
Author(s):  
Yingming Guo ◽  
Jianmin Zhang ◽  
Xi Chen ◽  
Jing Yang ◽  
Jianxiong Huang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
X Ray ◽  
First Order ◽  
Sand Surface ◽  
First Order Kinetics ◽  
Start Up ◽  
Do Concentration ◽  
Iron Manganese

AbstractTo shorten the ripening period of filter sand, iron–manganese co-oxide filter film (MeOx) was formed quickly on the virgin quartz sand surface by oxidizing Mn2+ and Fe2+ from groundwater using KMnO4 continuously. After the start-up period, we found that Mn2+ could be removed efficiently by MeOx, even if the dissolved oxygen (DO) concentration in the influent was only about 1.0–1.5 mg/L. This means that the removal process of Mn2+ does not need to consume DO. The kinetic experiments for Mn2+ indicated that the adsorption and oxidation kinetics followed pseudo-first-order kinetics. The film (MeOx) was characterized by X-ray photoelectron spectroscopy (XPS). All manganese adsorbed on the surface of the sand was the oxidized form, and the manganese oxide coated onto the sand effectively oxidized Mn2+ to Mn3+ or Mn4+. The binding energy of the observed photoelectron peaks of O(1s) showed the existence of [≡Mn-OH] on the surface of the film by XPS, which might be a key intermediate in the mechanism of Mn2+ oxidation. Finally, a chemical catalytic oxidation mechanism for Mn2+ removal was proposed by the analysis of the oxidation process.

Sr/Si Template Formation for the Epitaxial Growth of SrTiO3 on Silicon

2002 ◽  
Vol 716 ◽  
Author(s):  
Xiaoming Hu ◽  
Y. Liang ◽  
Yi Wei ◽  
J.L. Edwards ◽  
R. Droopad ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Epitaxial Growth ◽  
Photoelectron Spectroscopy ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
Metal Thin Films ◽  
X Ray ◽  
In Situ Techniques ◽  
Interfacial Structures

AbstractA novel silicon cleaning process using strontium metal thin films has been described. The silicon dioxide de-oxidation process using strontium as catalysts has been studied by X-ray Photoelectron Spectroscopy (XPS) and other in-situ techniques. A Sr/Si template for the epitaxial growth of SrTiO3 single crystals on silicon can be directly formed as a result of the above Sr-de-oxidation process. The de-oxidation mechanism can be explained after solving the interfacial structures of the Sr/SiO2/Si system with in-situ XPS.

Revealing the mechanism of the early stages of Ni–W RABiTS oxidation

2010 ◽  
Vol 25 (12) ◽  
pp. 2362-2370 ◽  
Author(s):  
Andrey V. Blednov ◽  
Oleg Yu. Gorbenko ◽  
Dmitriy P. Rodionov ◽  
Andrey R. Kaul
Keyword(s):  
Internal Oxidation ◽  
Photoelectron Spectroscopy ◽  
Oxidation Mechanism ◽  
Surface Oxidation ◽  
Surface Region ◽  
Near Surface ◽  
Precise Position ◽  
X Ray ◽  
Early Stages ◽  
Phase And Chemical Composition

The early stages of surface oxidation of biaxially textured Ni–W tapes were studied using thermodynamic calculations along with experimental tape oxidation at low P(O2). Tape phase and chemical composition, surface morphology, and roughness were examined using x-ray diffraction (XRD), energy-dispersive x-ray analysis (EDX), secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For a Ni0.95W0.05 alloy tape, the precise position of the tape oxidation line in P(O2)–T coordinates was established. This line includes a break at T ≈ 650 °C that originates from the change of the W oxidation mechanism from internal oxidation to oxidation on a free surface accompanied by segregation of the alloy components in the tape near-surface region. The surface roughness of a polished tape increased drastically during internal oxidation of W; further tape oxidation did not affect the integral roughness parameters, but introduced numerous small (˜;100 nm) features on the tape surface comprising NiO precipitates.

Ellipsometric and XPS Studies of 4H-SiC/SiO2 Interfaces, and Sacrificial Oxide Stripped 4H-SiC Surfaces

2006 ◽  
Vol 527-529 ◽  
pp. 1027-1030 ◽  
Author(s):  
Owen J. Guy ◽  
L. Chen ◽  
G. Pope ◽  
K.S. Teng ◽  
T. Maffeis ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Interfacial Layer ◽  
Oxidation Process ◽  
Silicon Layer ◽  
Subsequent Removal ◽  
X Ray ◽  
Mos Devices ◽  
Device Processing ◽  
Form Features ◽  
Silicon Oxygen

The investigation of the silicon carbide surface after a sacrificial silicon oxidation technique is reported. Oxidation of SiC is a necessary step in the fabrication of MOS devices and device termination features such as field plates. Device processing requires the etching of windows through the oxide layer to form features such as metal / SiC contacts. However, this work indicates that a thin interfacial Si-O-C layer is still present after etching the oxide with hydrofluric acid (HF). Ellipsometry and X-ray photoelectron spectroscopy (XPS) have been used to evaluate this interfacial layer formed after oxide growth and after subsequent removal of oxide layers. An XPS analysis of the surface after removal of the oxide revealed that silicon, oxygen and carbon were all present in the remaining layer, which could not be removed by annealing at temperatures up to 1000°C. The Si-O-C layer could be eliminated by altering the oxidation conditions or by using a sacrificial silicon layer oxidation process. Ni Schottky barrier diodes fabricated on the 4H-SiC surface after removal of the oxide, displayed slightly higher ideality factors than those of diodes fabricated on untreated 4H-SiC samples.

Near-threshold ultraviolet-laser ablation of Kapton film investigated by x-ray photoelectron spectroscopy

2003 ◽  
Vol 18 (1) ◽  
pp. 53-59 ◽  
Author(s):  
D. W. Zeng ◽  
K. C. Yung ◽  
C. S. Xie
Keyword(s):  
Free Radical ◽  
Photoelectron Spectroscopy ◽  
Oxidation Reaction ◽  
Oxidation Mechanism ◽  
Pulse Number ◽  
Ultraviolet Laser ◽  
Thermally Induced ◽  
X Ray ◽  
Induced Decomposition ◽  
Near Threshold

Near-threshold ultraviolet-laser (355 nm) ablation of 125-μm thick Kapton films was investigated in detail using x-ray photoelectron spectroscopy. Different from the irradiation at higher fluences, the contents of the oxygen, amide group, and C–O group on the ablated surface increased with an increase in the pulse number, whereas the carbon contents decreased, although the contents of the nitrogen and the carbonyl group (C = O) decreased slightly. This implied that there was no carbon-rich residue on the ablated surface. Near the ablation threshold, only photolysis of the C–N bond in the imide rings and the diaryl ether group (C–O) took place due to a low surface temperature rise, and the amide structure and many unstable free radical groups were created. Sequentially, the oxidation reaction occurred to stabilize the free radical groups. The decomposition and oxidation mechanism could explain the intriguing changes of the chemical composition and characteristics of the ablated surface. In addition, the content of the C–O group depended on the opposite factors: the thermally induced decomposition of the ether groups and the pyrolysis of the Caryl–C bond. Upon further irradiation, the cumulative heating may induce the breakage of the Caryl–C bond and enhance the oxidation reaction, resulting in an increase of the content of the C–O group.

OBSERVATION OF PHASE TRANSITIONS AT THE (100) SURFACE OF Al-3 at.% Ag

1995 ◽  
Vol 02 (02) ◽  
pp. 141-145 ◽  
Author(s):  
E. WETLI ◽  
M. HOCHSTRASSER ◽  
D. PESCIA ◽  
M. ERBUDAK
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Photoelectron Spectroscopy ◽  
Short Range ◽  
Short Range Order ◽  
Elevated Temperatures ◽  
X Ray ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

In the bulk binary alloy Al-3 at.% Ag , Ag 2 Al precipitates are formed below 410°C which are reversibly dissolved at elevated temperatures. We have followed this phase transition at a (100) surface as a function of temperature by monitoring the bandwidth of the Ag 4d states in X-ray photoelectron spectroscopy. Since the bandwidth measures the coordination number of the emitting atoms, it directly reveals the short-range order of the Ag atoms at the surface. The measurements show that the dissolution of the Ag -rich clusters starts at temperatures at least 100 K below the bulk transition, and the observed hysteresis behavior is indicative of a first-order phase transition at the surface.

Radicals induced from peroxomonosulfate by nanoscale zero-valent copper in the acidic solution

2016 ◽  
Vol 74 (8) ◽  
pp. 1946-1952 ◽  
Author(s):  
Peng Zhou ◽  
Bei Liu ◽  
Jing Zhang ◽  
Yongli Zhang ◽  
Gucheng Zhang ◽  
...  
Keyword(s):  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
Acidic Solution ◽  
Butyl Alcohol ◽  
First Order ◽  
First Order Kinetics ◽  
Tert Butyl Alcohol ◽  
Initial Ph ◽  
Reactive Radicals ◽  
Reactive Oxidant

A highly efficient advanced oxidation process for the degradation of benzoic acid (BA) during activation of peroxomonosulfate (PMS) by nanoscale zero-valent copper (nZVC) in acidic solution is reported. BA degradation was almost completely achieved after 10 min in the nZVC/PMS process at initial pH 3.0. PMS could accelerate the corrosion of nZVC in acidic to release Cu+ which can further activate PMS to produce reactive radicals. Both sulfate radical (SO4−•) and hydroxyl radical (•OH) were considered as the primary reactive oxidant in the nZVC/PMS process with the experiments of methyl (MA) and tert-butyl alcohol quenching. Acidic condition (initial pH ≤ 3.0) facilitated BA degradation and pH is a decisive factor to affect the oxidation capacity in the nZVC/PMS process. Moreover, BA degradation in the nZVC/PMS process followed the pseudo-first-order kinetics, and BA degradation efficiency increased with the increase of the nZVC dosage.

Oxidation Resistance of Multicomponent CrTiAlN Hard Coatings at Elevated Temperatures

2009 ◽  
Vol 75 ◽  
pp. 37-42
Author(s):  
P.L. Tam ◽  
Zhi Feng Zhou ◽  
P.W. Shum ◽  
K.Y. Li
Keyword(s):  
Oxidation Resistance ◽  
Photoelectron Spectroscopy ◽  
High Speed ◽  
Elevated Temperatures ◽  
Oxidation Mechanism ◽  
Hard Coatings ◽  
Closed Field ◽  
X Ray ◽  
Mechanical And Tribological Properties ◽  
Pin On Disc

Quaternary CrTiAlN hard coatings were deposited by closed field unbalanced magnetron sputtering ion plating technique onto steel substrates, and their structural, mechanical, and tribological properties after heat treatment in air at different temperatures (500-900 oC) were studied and compared by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-indentation, and pin-on-disc (POD) tribometer, etc. The onset temperature of oxidation was determined by thermogravimetric analyser (TGA). The compositional depth profiles before and after the heat treatments were examined by X-ray photoelectron spectroscopy (XPS) in order to study the oxidation mechanism. The experimental results indicate that the CrTiAlN coatings have excellent oxidation resistance and thermal stability, and outperform the traditional hard coatings like TiN and TiAlN in terms of higher oxidation temperature, hardness, adhesion, and wear resistance. It is expected that the CrTiAlN coatings with superior properties should have better performance in dry high speed machining.

scholarly journals Photoperoxidation of ciprofloxacin antibiotic in aqueous medium using Fe3-XO4-Y-TiO2 particles as catalyst

2022 ◽  
Vol 47 (1) ◽  
pp. 55-63
Author(s):  
Ismael Laurindo Costa Junior ◽  
Kevin Augusto Ferreira ◽  
Cesar Augusto Kappes ◽  
Renata Mello Giona
Keyword(s):  
Conventional Treatment ◽  
H2o2 Concentration ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Order ◽  
Tio2 Particles ◽  
Treatment Processes ◽  
First Order Kinetics ◽  
Heat Treated ◽  
Oxidative Processes

Conventional treatment processes are not effective in removing micropollutants such as antibiotics and other drugs present in wastewater, and degradation methods based on advanced oxidative processes become attractive. Herein, it was synthesized Fe3-xO4-y-TiO2 particles by coprecipitation method and they were heat-treated at 100, 400, and 800 �C. The obtained solids were characterized by X-ray diffraction and thermogravimetric analysis and analytical determinations were performed using ultraviolet-visible (UV-Vis) spectrophotometry. The particles were evaluated in photoperoxidation processes on the degradation of the ciprofloxacin antimicrobial in an aqueous solution. The studies took place at pH 9; with an H2O2 concentration of 31 mg L�1 and particle mass 0.22 g L�1 previously defined and, in these conditions, degradation percentages between 40 and 85% were observed, with the removal in the Photo/H2O2/Fe3-xO4-y-TiO2 800 �C. The kinetic study performed for this process revealed the process adjusts to the first-order kinetics during the 120 min of reaction. The use of the catalyst can be attractive with the potential for degradation of the studied antimicrobial.

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