scholarly journals Photocatalytic Treatment of Different Types of High−Concentration Ammonia Wastewater by Cu/TiO2 Film and its Mechanism Study

2021 ◽  
Author(s):  
Jianpei Feng ◽  
Guan Zhang ◽  
Xiaolei Zhang ◽  
Ji Li
Keyword(s):  
Photocatalytic Oxidation ◽  
Ammonia Oxidation ◽  
Oxidation Process ◽  
Aerobic Oxidation ◽  
Oxidation Mechanism ◽  
Mechanism Study ◽  
High Concentration ◽  
Solid Substrates ◽  
Different Types ◽  
Oxidation Of Ammonia

Abstract Photocatalytic oxidation of ammonia in wastewater has been abundantly investigated in lab − scale, but there are still many issues to be solved towards practical application. Herein, we have immobilized Cu/TiO2 photocatalyst on different solid substrates in order to practically utilize and recycle the photocatalyst during wastewater treatment, on the basis of exploring the effects of different influencing factors such as pH, temperature and salinity on the photocatalytic oxidation of ammonia in this work. The performance of Cu/TiO2 films was evaluated by circulated treatment of different types of wastewater including high salinity ammonia wastewater, copper − ammonia wastewater and liquid − ammonia mercerization wastewater. The characters of wastewater matrices significantly influence the performance for ammonia oxidation. Different from the slurry test of photocatalyst power that operated in a closed reactor, it is importantly found that oxygen in air plays significant role in photocatalytic oxidation of ammonia into dinitrogen in the aerobic oxidation process, when the Cu/TiO2 films were employed. The possible oxidation mechanism has been proposed to elucidate the ammonia oxidation process.

Investigation of Phthalocyanine Catalysts for the Aerobic Synthesis of meso-Substituted Porphyrins

1997 ◽  
Vol 01 (04) ◽  
pp. 385-394 ◽  
Author(s):  
M. RAVIKANTH ◽  
CATALINA ACHIM ◽  
JOHN S. TYHONAS ◽  
ECKARD MÜNCK ◽  
JONATHAN S. LINDSEY
Keyword(s):  
Trifluoroacetic Acid ◽  
Room Temperature ◽  
Heterogeneous Catalysts ◽  
Mossbauer Spectroscopy ◽  
Oxidation Process ◽  
Aerobic Oxidation ◽  
Heterogeneous Reactions ◽  
High Concentration ◽  
Neutral Conditions ◽  
Homogeneous Reactions

The aerobic oxidation process for the synthesis of porphyrins, previously performed using 5 mol % p-chloranil (TCQ), 5 mol % iron(II) phthalocyanine ( FePc ) and stoichiometric amounts of O 2, has been refined using new phthalocyanine catalysts. Four phthalocyanine catalysts have been prepared, characterized by Mössbauer spectroscopy and examined for efficacy in the high concentration (0.1 M) synthesis of tetraphenylporphyrin at room temperature. Each phthalocyanine has been identified to be a μ-oxo dimer. Two catalysts are soluble (the μ-oxo dimers [(t-butyl)4 FePc ]2 O and [(n- C 6 H 13 O )4 FePc ]2 O ) and enable homogeneous reactions, while two are insoluble (the μ-oxo(1) and μ-oxo(2) dimers of FePc , ( FePc )2 O ) and give heterogeneous reactions. These four phthalocyanine compounds provide efficient catalysis at the 0.3–1 mol % level using only 1 mol % quinone or hydroquinone ( TCQ , DDQ , TCQH 2 or DDQH 2), affording ~25% yields of tetraphenylporphyrin in 60 min of oxidation. There are no discernible advantages of the homogeneous versus heterogeneous catalysts. The μ-oxo dimers are active, but FePc is inactive, at the 0.3 mol % level. The activity of the FePc sample at the 5 mol % level is attributed to residual μ-oxo dimer impurity. This aerobic oxidation process is superior to stoichiometric oxidation with TCQ or DDQ , and can be performed in the presence of BF 3· O ( Et )2, trifluoroacetic acid, or under neutral conditions.

scholarly journals Soils and sediments host novel archaea with divergent monooxygenases implicated in ammonia oxidation

2021 ◽  
Author(s):  
Spencer Diamond ◽  
Adi Lavy ◽  
Alexander Crits-Christoph ◽  
Paula B. Matheus Carnevali ◽  
Allison Sharrar ◽  
...  
Keyword(s):  
Amino Acid ◽  
Electron Transport ◽  
Carbon Fixation ◽  
Ammonia Oxidation ◽  
Aerobic Oxidation ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Copper Proteins ◽  
Soils And Sediments ◽  
Oxidation Of Ammonia

Copper membrane monooxygenases (CuMMOs) play critical roles in the global carbon and nitrogen cycles. Organisms harboring these enzymes perform the first, and rate limiting, step in aerobic oxidation of ammonia, methane, or other simple hydrocarbons. Within archaea, only organisms in the order Nitrososphaerales (Thaumarchaeota) encode CuMMOs, which function exclusively as ammonia monooxygenases. From grassland and hillslope soils and aquifer sediments, we identified 20 genomes from distinct archaeal species encoding divergent CuMMO sequences. These archaea are phylogenetically clustered in a previously unnamed Thermoplasmatota order, herein named the Ca. Angelarcheales. The CuMMO proteins in Ca. Angelarcheales are more similar in structure to those in ammonia-oxidizing archaea than those of bacteria, and they contain all functional residues required for activity. Similarly to the Nitrososphaerales, Ca. Angelarcheales genomes are significantly enriched in blue copper proteins (BCPs) relative to sibling lineages, including plastocyanin-like electron carriers and divergent nitrite reductase-like (nirK) 2-domain cupredoxin proteins co-located with electron transport machinery. Angelarcheales do not have identifiable genes for methanol oxidation or carbon fixation, encode significant capacity for peptide/amino acid uptake and degradation, and share numerous electron transport mechanisms with the Nitrososphaerales. In the studied soils and sediments Ca. Angelarcheales were at least as abundant as ammonia-oxidizing Nitrososphaerales. Thus, we predict that Angelarcheales live a mixotrophic lifestyle based on oxidation of ammonia liberated from peptide and amino acid degradation. This work expands the known diversity of Thermoplasmatota and of CuMMO enzymes in archaea and suggests that these organisms are important and previously unaccounted for contributors to nitrogen cycling.

scholarly journals Graphene quantum dot modified g-C3N4 for enhanced photocatalytic oxidation of ammonia performance

RSC Advances ◽  
2017 ◽  
Vol 7 (81) ◽  
pp. 51687-51694 ◽  
Author(s):  
Ruiling Wang ◽  
Tian Xie ◽  
Zhiyong Sun ◽  
Taofei Pu ◽  
Weibing Li ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Photocatalytic Oxidation ◽  
Ammonia Oxidation ◽  
Graphene Quantum Dot ◽  
Composite Photocatalysts ◽  
Oxidation Of Ammonia

Graphene quantum dot modified g-C3N4 composite photocatalysts were prepared and their photocatalytic ammonia oxidation performances were studied.

EFFICIENT DEGRADATION OF CLOFIBRIC ACID BY HETEROGENEOUS PHOTOCATALYTIC OXIDATION PROCESS

2019 ◽  
Vol 18 (8) ◽  
pp. 1683-1692 ◽  
Author(s):  
Lidia Favier ◽  
Lacramioara Rusu ◽  
Andrei Ionut Simion ◽  
Raluca Maria Hlihor ◽  
Mariana Liliana Pacala ◽  
...  
Keyword(s):  
Photocatalytic Oxidation ◽  
Oxidation Process ◽  
Clofibric Acid

Improved photocatalytic conversion of high−concentration ammonia in water by low−cost Cu/TiO2 and its mechanism study

Chemosphere ◽  
2021 ◽  
Vol 274 ◽  
pp. 129689
Author(s):  
Jianpei Feng ◽  
Xiaolei Zhang ◽  
Guan Zhang ◽  
Ji Li ◽  
Wei Song ◽  
...  
Keyword(s):  
Low Cost ◽  
Mechanism Study ◽  
High Concentration

A review on TiO2-based composites for superior photocatalytic activity

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wail Al Zoubi ◽  
Abbas Ali Salih Al-Hamdani ◽  
Baek Sunghun ◽  
Young Gun Ko
Keyword(s):  
Photocatalytic Activity ◽  
Organic Pollutants ◽  
Cost Efficiency ◽  
High Stability ◽  
Photocatalytic Oxidation ◽  
Oxidation Process ◽  
Ambient Conditions ◽  
Photoelectrochemical Activity ◽  
As Doping ◽  
Degradation Of Pollutants

Abstract Heterogeneous photocatalysts was a promising material for removing organic pollutants. Titanium dioxide (TiO2) was a suitable photocatalyst for its cost efficiency and high stability to reduce various pollutants. Enhancing TiO2 photocatalyst performance by doping with changed metals or non-metal ions and organic compounds have been reviewed. These methods could enhance photoelectrochemical activity via: (i) by a donor of electrons via electron-donor agents that would produce particular defects in TiO2 structure and capture transporters of charge; (ii) by reducing recombination rate of the charge transporters and increasing degradation of pollutants. This study investigates the modification approaches of TiO2 that comprise methods for overcoming the essential TiO2 restrictions and enhancing the photocatalytic degradation of organic pollutants. Consequently, it emphasized on the current progress of modified-TiO2 used for different pollutants in ambient conditions. Amendment techniques, such as inorganic and organic parts as doping, are studied. The reported experimental results obtained with the photocatalytic oxidation process for degrading organic pollutants were also collected and assessed.

scholarly journals Heterogeneous Photo-Fenton Catalytic Degradation of Practical Pharmaceutical Wastewater by Modified Attapulgite Supported Multi-Metal Oxides

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 156
Author(s):  
Manjing Lu ◽  
Jiaqi Wang ◽  
Yuzhong Wang ◽  
Zhengguang He
Keyword(s):  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Catalytic Degradation ◽  
Gas Chromatography Mass Spectrometry ◽  
Pharmaceutical Wastewater ◽  
High Concentration ◽  
Modified Attapulgite ◽  
Cod Removal Rate ◽  
Pre Treatment ◽  
Almost All

Chemical synthetic pharmaceutical wastewater has characteristics of high concentration, high toxicity and poor biodegradability, so it is difficult to directly biodegrade. We used acid modified attapulgite (ATP) supported Fe-Mn-Cu polymetallic oxide as catalyst for multi-phase Fenton-like ultraviolet photocatalytic oxidation (photo-Fenton) treatment with actual chemical synthetic pharmaceutical wastewater as the treatment object. The results showed that at the initial pH of 2.0, light distance of 20 cm, and catalyst dosage and hydrogen peroxide concentration of 10.0 g/L and 0.5 mol/L respectively, the COD removal rate of wastewater reached 65% and BOD5/COD increased to 0.387 when the reaction lasted for 180 min. The results of gas chromatography-mass spectrometry (GC-MS) indicated that Fenton-like reaction with Fe-Mn-Cu@ATP had good catalytic potential and significant synergistic effect, and could remove almost all heterocycle compounds well. 3D-EEM (3D electron microscope) fluorescence spectra showed that the fluorescence intensity decreased significantly during catalytic degradation, and the UV humus-like and fulvic acid were effectively removed. The degradation efficiency of the nanocomposite only decreased by 5.8% after repeated use for 6 cycles. It seems appropriate to use this process as a pre-treatment for actual pharmaceutical wastewater to facilitate further biological treatment.

First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

2015 ◽  
Vol 14 (03) ◽  
pp. 1550020 ◽  
Author(s):  
Yuan Yuan ◽  
Wei Hu ◽  
Xuhui Chi ◽  
Cuihua Li ◽  
Dayong Gui ◽  
...  
Keyword(s):  
Diethyl Ether ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
High Energy ◽  
First Principle ◽  
Functional Theory ◽  
The Third ◽  
High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

Temperature-Driven Oxidation Behavior of Pure Iron Surface Investigated by Time-Resolved EXAFS Measurements

1998 ◽  
Vol 524 ◽  
Author(s):  
S. J. Doh ◽  
J. M. Lee ◽  
D. Y. Noh ◽  
J. H. Je
Keyword(s):  
Heat Treatment ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Rapid Heating ◽  
Oxidation Mechanism ◽  
Front Surface ◽  
Time Resolved ◽  
Treatment Conditions ◽  
Surface Front ◽  
Prolonged Heat

ABSTRACTThe surface-front oxidation mechanism of iron was investigated by time-resolved, glancingangle Fe K-edge fluorescence EXAFS measurements at various oxidation temperatures of 200-700 C. The glancing angle was chosen according to the depth of the oxide layer, roughly 1500-2000A. The oxidation behavior under rapid heating(up to 600°C within 10 minutes) was compared with the slowly heated oxidation process using the Quick-EXAFS measurements. In the slowly heated process, Fe3O4 was the dominating phase at a relatively low temperature (300-400 C) initially. However, at a relatively high temperature (above 600°C), the Fe2O3 and FeO crystalline phases are gradually enriched as the successive oxidation process involving intrusive oxygen proceeded. Remarkably under a prolonged heat treatment above 600°C, the stable FeO phase that exists in a deep-lying interface structure and Fe2O3 phase eventually dominates the thick front-surface structure. In a quickly heated process, however, Fe3O4 phase is less dominating, which is contradictory to the commonly accepted oxidation models. The EXAFS results are discussed in conjunction with the x-ray diffraction features under the same heat treatment conditions.

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