Top PDF Iron catalysis in oxidation by ozone

Iron catalysis in oxidation by ozone

Iron catalysis in oxidation by ozone

In the experiment With 1 13 mM DMSO, the larg est peak at m/Z:78 Was due to DMSO from incomplete separation betWeen DMSO and methyl sulfone at such 40 high DMSO, concentration Conditions[r]

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Studies on Ozone-oxidation of Dye in a Bubble Column Reactor at Different pH and Different Oxidation-reduction Potential

Studies on Ozone-oxidation of Dye in a Bubble Column Reactor at Different pH and Different Oxidation-reduction Potential

341 Abstract—A massive and considerable amount of effluent is generated in a textile industry and allied industries. Dyes used in the dyeing section of a textile industry is a constant, intense and persistent source of concern to the environmental engineer and to the common mass in general. This dye effluent/waste cannot be degraded with the help of primary and secondary treatments. Primary treatment involves coagulation and flocculation while secondary treatment encompasses activated sludge process. So the importance , urgency and aim of a tertiary treatment process such as ozone-oxidation or ozonation. The present research engulfs the understanding of the dependence of order of reaction on pH of the solution and oxidation-reduction potential. The research on ozonation of dye is done in a bubble column reactor-fixed bed and without media . It gives an understanding and an innovative concept that dye degradation by ozonation is highly dependent on acidity or alkalinity of solution. Investigations in the variation of redox potentials in the course of ozonation reaction is also analysed. The vision, mission and objective of the area of tertiary treatment or degradation by ozonation will be greatly enunciated if the research endeavour progresses with the help of a tool such as bubble column reactor.
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Study  on the treatment  of high  concentration  organic  waste water by  ozone advanced chemical  oxidation

Study on the treatment of high concentration organic waste water by ozone advanced chemical oxidation

It can be seen in Figure 3-4 that the chromatic ity of water reduced with o xidation time . Especially in ea rly o zone oxidation stages, this decrease was significant. Afterwa rds, the rate became slow. The reason for this is that ozone degraded some organics in the wastewater, however, there were other un -degradable organics, leading the variation of chromatic ity became sma ller and smaller. It can be concluded that there is an optimu m o xidation time for the treatment of wastewater using ozone. According to the data and Figure 3-4, this optimu m o xidation time is 30min. In this case, the value of chromatic ity dropped fro m 142 mg/L to 8 mg/L and the re moval rate of chro matic ity reached 94.37%.
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Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

During the analysis of other experiments being carried out in the CLOUD chamber (ozone initiated oxidation of iso- prene), high precision measurements of gas phase gyoxal were performed. During these measurements, it was found that as soon as the pressure decrease associated with an ex- pansion began, the gas phase glyoxal increased rapidly from around 50 pptv to almost 500 pptv (Fig. 9). Glyoxal is rela- tively soluble, with an effective Henrys law coefficient of ap- proximately 4 × 10 5 M atm −1 at 298 K in pure water (Ip et al., 2009), a value that increases by orders of magnitude for solu- tions containing sulphate (Ip et al., 2009; Kampf et al., 2013). Therefore this gas phase increase occurs in spite of the simul- taneous uptake by the droplets. Ammonia is comparably sol- uble, with the effective Henry’s law coefficient ranging be- tween approximately 1 × 10 4 M atm −1 for a solution pH of 7, and 1 × 10 7 M atm −1 when the pH is 4 (Seinfeld and Pandis, 2006). It is possible that the pressure change and increased turbulence during the decompression of the chamber lead to a better ventilation of the chamber walls. This would be char- acterised by a higher eddy diffusion coefficient, increasing the rate of exchange between the gas phase and the walls
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Catalytic ozone oxidation of benzene at low temperature over MnOx/Al SBA 16 catalyst

Catalytic ozone oxidation of benzene at low temperature over MnOx/Al SBA 16 catalyst

Ozone has been widely used for pollution treatment in the semiconductor industry, water treatment, and air cleaning [3-5]. In particular, catalytic ozone oxidation has high pollutant-removal efficiency and low energy consumption [6]. In the catalytic ozone oxidation pro- cess, ozone is decomposed into activated oxygen species that can oxidize organic compounds. Recently, researches on the catalytic ozone oxidation of volatile organic compounds [VOCs] including HAPs have been

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Ozone oxidation methods for aluminium oxide formation : application to low-voltage organic transistors

Ozone oxidation methods for aluminium oxide formation : application to low-voltage organic transistors

Four different methods of ozone generation have been imple- mented. The first one used UV/ozone cleaner (UVOCS) enclosed under a Hepa filter under ambient environmental conditions (21 °C, relative air humidity of 45%). In the second case a flow of dry air (21 °C, relative air humidity 6 0.1%) was supplied into the UV/ozone cleaner, while the remaining parameters were kept the same. In the third case, dry air passed through high-voltage ozone generator (A2Z Ozone) and the generated ozone was sup- plied into the running UV/ozone cleaner (mercury lamp was on). Finally, the fourth method was similar to the third one, except the mercury lamp was turned off. This condition aimed to investi- gate the role of UV photons illuminating the aluminum layers dur- ing their oxidation. These four methods are summarized in Table 1. All samples were prepared on Eagle 2000 glass substrates. Samples for spectroscopic ellipsometry, X-ray photoelectron spec- troscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) started with 30-nm-thick thermally evaporated Al layers. Samples were oxidized according to the conditions shown in Table 1 and the oxidation time was 2 h. The fifth sample was left to oxidize in dark ambient conditions to form a native oxide (Native AA). Finally, the UV-AA oxidation ranging from 5 min to 6 h was used to produce 6 samples. This allowed studying the thickness of the UV-AA AlO x as a function of oxidation time.
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Advanced Oxidation Treatment of Composting Leachate of Food Solid Waste by Ozone-Hydrogen Peroxide

Advanced Oxidation Treatment of Composting Leachate of Food Solid Waste by Ozone-Hydrogen Peroxide

The advanced leachate oxidation process was carried out in a flow glass reactor. The reactor is equipped with a stirrer, by means of which it is possible to aerate the mixture with the ozone coming from the discharge generator. Through the system of independent infusions, the leachates and the hydrogen peroxide solution are infused into the reaction chamber. The AOP procedure proceeded according to the following scheme: 1. Filling the reactor with 1 dm 3 of the leachate,

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Ozone oxidation pretreatment for enzymatic saccharification of spent culture media after Lentinula edodes cultivation

Ozone oxidation pretreatment for enzymatic saccharification of spent culture media after Lentinula edodes cultivation

Ozone was generated by an ozone generator (ED-OG- R6, Ecodesign). Oxygen flow rate was adjusted to 50 mL/ min, and the electrical power level of the ozone generator was adjusted to 100 %. The concentration of ozone gen- erated was measured according to the conventional iodo- metric method [19]. The ozone concentration was 6 % under these conditions. MCs of samples were adjusted to 20, 40, 60, and 80 %, respectively. One gram of wet sample was placed into a 100 mL eggplant-shaped flask, and then the flask was connected to a rotary evaporator (N- 1110N, EYELA). The ozone oxidation treatment of SCM was performed at 45 rpm with 6.0 % (w/w) ozone at RT for 0.5, 1.0, and 2.0 h. After oxidation, the samples were dried at 45 °C for 1–2 days. Contents of Klason lignin, holocellulose, and a-cellulose were determined according to the standard methods [20].
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Ozone oxidation of antidepressants in wastewater –Treatment evaluation and characterization of new by-products by LC-QToFMS

Ozone oxidation of antidepressants in wastewater –Treatment evaluation and characterization of new by-products by LC-QToFMS

position through the formation of chain intermediate free radicals, including the hydroxyl radical OH• (less selective reaction on saturated aliphatic molecules) [26,28]. The stability of dissolved ozone is readily affected by pH, ultra- violet (UV) light, ozone concentration, and the concentra- tion of radical scavengers such carbonate – bicarbonate species, the dissolved organic carbon and humic acids [28,29]. Except for few experiments completed with fluoxe- tine (FLU), the number of studies dedicated to the elimi- nation of antidepressants by oxidation processes (e.g. TiO 2
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Ozone Treatment of Municipal Wastewater Effluent for Oxidation of Emerging Contaminants and Disinfection

Ozone Treatment of Municipal Wastewater Effluent for Oxidation of Emerging Contaminants and Disinfection

disinfection technology (Drury et al., 2006; Oneby et al., 2010). These developments have led to a huge surge in research related to ozone treatment of secondary and tertiary treated municipal wastewater the world over in recent years. While studies have demonstrated the potential for ozonation to transform effectively many CECs present in MWWE, such studies are still limited both in number and list of CECs examined. Studies have further shown that the effectiveness of such transformations by ozone is strongly dependent on the properties of the CEC and the matrix, particularly the nature and concentration of dissolved organic carbon. In addition, the list of CECs in the water environment continues to grow. Hence, there is a continued need to study the ozone and ozone-based advanced oxidation processes (AOPs) for different wastewater matrices and CEC groups to better understand and apply them for wastewater treatment. Ozone treatment of municipal wastewater in Canada for disinfection has been studied and is being considered as a special circumstance for the primary treated wastewater effluent in the City of Montreal. However, to the best knowledge of the author, study on disinfection and oxidation of CECs using ozone for treatment of the more common secondary treated municipal wastewater effluent has not been conducted in Canada.
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A Study on the Removal of Fluorescent Whitening Agent by Pretreatment Ozone Oxidation for MBR Process Application

A Study on the Removal of Fluorescent Whitening Agent by Pretreatment Ozone Oxidation for MBR Process Application

wavelength of the long wavelength zone[9]. Removal of the chromophore occurred from the starting point of the ozone oxidation where the maximum absorption wavelength was 380 nm in 5 minutes and below 350 nm in 30 minutes. Looking at this, it can be seen that the completion of the chromophore of the fluorescent whitening dye was completed within 30 minutes. Also, it was identified that the frequency of organic matters was diversified in 2-3 ABS zones of the organic matter wavelength due to the removal where the ozone oxidation became activated to go through various procedures of oxidation return to make decomposition of intermediate compounds possible. The removal of amino and sulfone inducing the combination of fiber and/or the fiber with the fluorescent whitening agent within 10 minutes of the ozone oxidation reaction time in the oxidation experiment of the diaminostilbene disulfonic acid derivative cause the main reaction, and it rapidly reacted with the ozone to create methyl and aldehyde[11,12]. From 30 minutes point, it led to the diaminostilbene sulfonic acid decomposition process to show removal rate of more than 50% in 90 minutes of the reaction time. The T-N concentration gradually increased between 5-10 minutes of the ozone oxidation time, and after 10 minutes the T-N concentration was stabilized. This is analyzed that the amino was probably the factor of increasing the concentration of T-N because the chromophore was removed due to ozone oxidation. However, it was identified in the analysis of chromaticity that the change was not significant. The chromaticity of the raw water being around 280 Pt/Co was because the chromaticity increased in the light brown wavelength of benzene. Thus,
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Iron cyclopentadienone complexes derived from C2 symmetric bis propargylic alcohols; preparation and applications to catalysis

Iron cyclopentadienone complexes derived from C2 symmetric bis propargylic alcohols; preparation and applications to catalysis

The complexes 13, 18 – 21 were first applied to the asym- metric reduction of the representative substrate acetophenone, using both asymmetric transfer hydrogenation (ATH) and pressure hydrogenation (APH) conditions. The complexes were also used in the oxidation of racemic 1-phenylethanol using acetone as a hydrogen acceptor. In all cases the active catalyst was generated in situ using methods previously reported, and in some cases comparisons with the unfunctionalised catalyst 4b 2b were also made. 2–12,15 In the ATH reactions (Table 2 shows selected results, further results are given in the ESI, Table S1 † ), at 60 °C using a 5 : 2 (molar) formic acid : triethyl- amine azeotrope (FA/TEA) and 10 mol% catalyst, full conver- sion was observed in several cases however the asymmetric inductions were extremely low and a significant amount of formate co-product was also formed, presumably through formylation of the initial alcohol product (confirmed to be of the same absolute configuration as the alcohol). 6a TMAO was added to ensure full activation of the catalysts efficiently although, as demonstrated using unsubstituted 4b, it could be omitted from the reaction 6a at the cost of a slower activation; a reaction complete in 24 h using TMAO reached just 52% con- version in the same time without TMAO (entries 1 – 3). In this respect, however the diol complex 13 appeared to be less sensi- tive to the additive (entries 4–7). Although the enantioselectivi- ties were low, the OH and OBn complexes gave products of opposite configurations to those observed with the O-silylated complexes (entries 8–15). The use of lower catalyst loadings (5%, 1%) gave much lower conversions, as did lowering the temperature to 40 °C (ESI † ). Another clear trend was the obser- vation of improved ees when using the more hindered silyl- substituted complexes, for both the alcohol and formate products.
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Synthesis and applications to catalysis of novel cyclopentadienone iron tricarbonyl complexes

Synthesis and applications to catalysis of novel cyclopentadienone iron tricarbonyl complexes

In conclusion, we have completed the synthesis of a range of enantiomerically-enriched cyclopentadienone iron tricarbonyl complexes through a range of diverse approaches, thus opening up routes to a range of valuable derivatives for testing as reduction and oxidation catalysts. Larger functional groups flank- ing the central C v O bond in the catalyst appear to give improved enantioselectivities in reductions, however even the best enantio- meric excesses were relatively modest. Whilst the synthesis of the iron-based catalysts was successful, the results indicate that sig- nificant work remains to be carried out in order to translate our understanding of the mechanism to the synthesis of a highly enantioselective catalyst for the target applications. This remains the subject of ongoing studies in our group.
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Compartmentalized catalysis

Compartmentalized catalysis

If homogeneous metal catalysts are enclosed in polymersomes, physical interaction with other catalytic species can be prevented, which contributes to an improved compatibility. Hence, metal catalyst-loaded polymersomes are highly interesting for cascade chemistry where compartmentalization is required. Until now, only a few examples exist in which metal- containing compounds were encapsulated in polymersomes or the closely related liposomes [34],[35],[36] and in none of these examples a homogeneous metal catalyst was involved. The lack of homogeneous metal catalyst encapsulation can be attributed to two main problems. First, polymersomes are usually prepared in water, whilst homogeneous metal catalysts are generally unstable and not reactive under aqueous conditions. Secondly, regular homogeneous metal catalysts would escape from the semipermeable compartment due to the small dimensions of these catalysts. Therefore, they should be immobilized on a support prior to encapsulation to prevent leakage. Immobilization on dendrimers would allow keeping the catalyst inside the vesicles, as diffusion through the membrane is hampered due to their large dimensions. Poly(propylene imine)-based (DAB-Am) dendrimers were chosen as support, as these well-defined macromolecules are water soluble, easy to adapt and commercially available. The preparation of water-soluble dendrimer-supported catalysts was described in chapter 3. These catalysts showed catalytic activity in an aqueous reductive amination. Additionally, proteins should be suitable supports as well, because these molecules are generally water soluble, commercially available and because proteins have been successfully enclosed in polymersomes before. Formation of metal complex-enzyme conjugates have been previously described, for example in order to obtain a chiral environment for enantioselective catalysis. [37] In some cases, the metal complexes were functionalized with biotin, which is strongly bound by streptavidin, [38],[39],[40] while another approach involved covalent attachment via cysteine conjugation. [41] The role of the protein in our approach differs from the examples mentioned above. The protein is used as a support rather than as protection or a chiral agent; protection in our case is achieved via the polymeric vesicles.
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Study on the Mechanism of Heterogeneous Catalysis (3) —The Catalysis of W, Mo, S and SiO2 on Carbon Dissolving and  Mechanism of Carbon Dissolving in the Iron Graphite Compact

Study on the Mechanism of Heterogeneous Catalysis (3) —The Catalysis of W, Mo, S and SiO2 on Carbon Dissolving and Mechanism of Carbon Dissolving in the Iron Graphite Compact

and think that the carbon is dissolved in the iron in a direct dissolving. Tanaka etc. [2] have also studied the catalytic effect of carbonates in iron-graphite compacts sintering, they have obtained similar results. But it’s completely different from that Hong [3] get. Author considers that the different experimental results are caused by inappropriate sintering temperature (1100˚C high temperature), time (long time), and atmosphere. The wrong experimental method will be to get unreliable experimental results

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Phase Stability of Iron Oxides on Palladium Iron Alloy at Elevated Temperatures and Its Application to High Temperature Oxidation

Phase Stability of Iron Oxides on Palladium Iron Alloy at Elevated Temperatures and Its Application to High Temperature Oxidation

independent of the composition of a two phase alloy, because a constant activity of Fe. The oxygen partial pressure calculated from the equilibrium emfs obtained by Alcock and Kubik 11) are also plotted in this figure. The oxygen partial pressures at higher iron content were close enough with their result but the difference reaches one order of magnitude higher at lower iron content. This difference may come from the change of Fe concentration in the alloy during the Emf measurement. Fe concentration in the alloy may be changed due to the oxidation with not only by the limited oxygen in the evacuated cell, but also oxygen which was
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Elimination of iron by processes of oxidation and by adsorption on coal of pine

Elimination of iron by processes of oxidation and by adsorption on coal of pine

Nous avons appliqué la même procédure d’adsorption en mode statique, nous avons mélangé 0,1g du charbon de bois de pin d’alep avec 100ml d’eau à analyser et nous avons fixé le temps d’[r]

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Thermophilic acidophilic bacteria: iron, sulphur and mineral oxidation

Thermophilic acidophilic bacteria: iron, sulphur and mineral oxidation

during autotrophic Iron oxidation growth of moderately thermophilic and the rapid dissolution of mineral acidophiles both during the moderate and the growth of autotrophic sulphides thus[r]

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Electrochemical kinetics and mechanisms of iron oxidation in CO2-containing aqueous monoethanolamine

Electrochemical kinetics and mechanisms of iron oxidation in CO2-containing aqueous monoethanolamine

As mentioned previously, an electrode reaction is in a state of dynamic equilibrium at its equilibrium potential at which no net reaction current flows. The anodic reaction (metal corrosion) can only occur at potentials more positive than the equilibrium potential and the cathodic reaction (oxidant reduction) proceeds at potentials more negative than its equilibrium potential. Thermodynamically it is known that the corrosion of metals in solutions is not only dependent on the electrode potential but also on the pH of the solution. Thus, when several reactions are possible, as is the case with Fe oxidation, the electrochemical behaviour in aqueous systems can be illustrated by Pourbaix diagrams in the form of phase stability plots which are created by relating the reversible potential to pH and total dissolved cation activity. These visual representations of the equilibrium conditions in the potential/pH space were pioneered by Professor Marcel Pourbaix (Bard, 2003). They are based purely on the thermodynamics and indicate the stability of predominant species under given conditions but give no indication of the rates of reactions from one phase to another.
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Facile Preparation of Pt/Polyallylamine/Reduced Graphene Oxide Composites and Their Application in the Electrochemical Catalysis on Methanol Oxidation

Facile Preparation of Pt/Polyallylamine/Reduced Graphene Oxide Composites and Their Application in the Electrochemical Catalysis on Methanol Oxidation

We demonstrate the use of PAA as an effective linker and stabilizer for the synthesis of Pt/PAA/RGO catalysts. The Pt nanoparticles are well distributed on the surface of RGO with an average diameter of 1.4 nm. As compared to Pt/RGO composites, the as-prepared Pt/PAA/RGO catalysts show a greater electroactive surface area due to their smaller size and higher dispersion of Pt nanoparticles on RGO. In addition, Pt/PAA/RGO catalysts are higher active in the electrochemical catalysis of methanol oxidation. Their peak current density is 310.6 mA·mg -1 , nearly quadrupling that at Pt/RGO catalysts. Moreover, Pt/PAA/RGO catalysts are more tolerant of CO poisoning. Their peak current ratio between the oxidation of methanol and adsorbed CO is 1.92, being higher than that of Pt/RGO catalysts (1.09). Impedance measurements indicate the formation of different reaction intermediates during the methanol oxidation process. The transition of capacitive to resistive at the lower potentials and resistive to pseudoinductive and then to inductive behaviors at high potentials have been observed at Pt/PAA/RGO catalysts. The electron transfer kinetics for the oxidation of methanol is fast at the potential of 0.4 with a characteristic of a pseudoinductive behavior, being different from a capacitive and resistive curve presented at Pt/RGO catalysts. In this potential, Pt/PAA/RGO catalysts favor the formation of the adsorbed hydroxyl species, which is available to the removal of CO species. Thus, the size and dispersion of Pt nanoparticles on the surface of RGO control the electrocatalytic performance of Pt catalysts and the molecular pathway of methanol oxidation at the surface of Pt catalysts.
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