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1.
In this research, the absorbed dose, background gases, relative humidity, and initial concentrations were selected as control factors to discover decomposition characteristics of styrene using electron beam irradiation. It was confirmed that a considerable amount of styrene was removed by primary electrons as well as radicals and ions, which were produced after the electron beam irradiation. Moreover, the removal efficiencies of styrene were observed to rise when the initial concentration was lower, moisture content was higher, and the absorbed dose increased. For instance, 50 ppmv styrene showed extremely high removal efficiency (over 98%) at a condition of 2.5 kGy. A small amount of styrene oxide, benzaldehyde, aerosol, CO, and CO 2 were produced as by-products after EB irradiation. 相似文献
2.
Electron beam (EB) technology has an advantage for treating dilute environmental pollutants in gases due to high-density population
of active species such as radicals and atoms. In general, OH radicals play an important role of initiating the decomposition
and removal of such pollutants. It is quite important to understand the behavior of OH radical production for the development
of efficient decomposition/removal processes and the comparison with other purification methods. The number of OH radicals
produced in humid N 2 at doses of 2.0–10.0 kGy with dose rates of 0.17–2.55 kGy/s under 1-MeV EB irradiation was indirectly determined using an
index of oxidation of CO to CO 2, which has been used in atmospheric chemistry. An experiment under conditions where all OH radicals produced react with CO
demonstrated that the concentration of CO 2 increased linearly with doses of 0–10 kGy, and the G(OH) was estimated as 4.90. 相似文献
3.
To identify the decomposition characteristics of trimethylamine (TMA) by electron beam (EB), we conducted an experiment based on process parameters, including absorbed dose (2.5–10 kGy), background gas (air, O 2, N 2 and He), water content (1,200, 14,300, and 27,500 ppm), initial concentration (50, 100, and 200 ppm) and reactor type (batch or continuous flow system). Air background gas showed a maximum TMA removal efficiency of 86 % at 10 kGy and that was the highest efficiency of all background gases. Energy efficiencies were higher when the absorbed dose was lower (e.g., 2.5 kGy). Decomposition efficiencies of all initial TMA concentrations were approximately >90 % at 10 kGy. Removal efficiencies increased up to 30 % as water vapor increased. As a by-product, it is observed that CH 3 radical formed by EB irradiation was converted into CH 4 by reaction with residual TMA, (CH 3) 2NH, and H. These results suggest that EB technology can be applied for TMA treatment under low concentration and high flow rate conditions. 相似文献
4.
The oxidation of xylene and its irradiation byproducts in air using TiO 2 was studied under electron beam (EB) irradiation for the purification of ventilation gases emitted from paint factories.
EB irradiation experiments were mainly performed under two different conditions: a TiO 2 pellet layer was placed in an irradiation or a non-irradiation space. The results revealed that xylene was decomposed and
CO was formed in the gas phase of the irradiation space irrespective of the presence of TiO 2 pellets, while CO 2 was produced in the gas phase of the irradiation space and on the surface of TiO 2 pellets. The total CO 2 concentration increased when the pellet layer was in the non-irradiation space. On the other hand, the concentration of CO 2 produced on the surface of the TiO 2 pellets in the irradiation space was higher than that in a non-irradiation space. 相似文献
5.
This research was conducted to determine the removal characteristics of butane, using an electron beam. Influential factors, such as an initial concentration, background gases (nitrogen, air, and helium), and absorbed doses (kGy) were investigated. The decomposition efficiencies of background gases showed that oxidation caused by radicals formed from gases, such as N 2 and O 2, had a greater influence on results than oxidation from primary electrons for butane removal. Removal efficiencies were 40% at 2.5 kGy and 66% at 10 kGy, when the initial concentration of butane was 60 ppmC. When the initial concentration was lower, the energy efficiency of butane removal by electron beam was higher. By-products, including CO 2, CO, acetaldehyde, and acetone, formed after electron beam irradiation. Concentrations of CO 2 and CO tended to increase when absorbed doses increased as butane was decomposed by the electron beam through an advanced oxidation. 相似文献
6.
An AC-pulsed tornado gliding arc plasma was employed for CO 2 conversion via CO 2 decomposition and dry reforming reactions. A stable and high-efficient constant arc length discharge mode was obtained in this plasma reactor. And then, CO 2 conversion was studied under this discharge mode. In the case of CH 4/CO 2 = 0, CO 2 was converted to CO and O 2 via the CO 2 decomposition reaction. Energy efficiency of 29 % was attained at CO 2 conversion of 6 %. With strong reducing agent CH 4 added into CO 2, the main contributor of CO 2 conversion changed from CO 2 decomposition to dry reforming of CH 4. Conversions of CH 4 and CO 2, energy efficiency and energy cost changed sharply at CO 2/CH 4 ratios lower than 1/4, while they changed slowly at CH 4/CO 2 ratios above 1/4. In the case of CH 4/CO 2 = 2/3, energy efficiency of 68 % and syngas energy cost of 1.6 eV/mole were achieved at CH 4 conversion of 29 % and CO 2 conversion of 22 %. 相似文献
7.
In the present work, the detailed reaction mechanism and possible products of the OH-initiated oxidation of CH 2=C(CH 3)CH 2CH 2OH (MBO331) have been revealed theoretically for the first time. The potential energy surfaces of various reaction channels
both in the absence and presence of O 2 and NO are evaluated at the CCSD(T)/6−31++G(d,p)//MP2(full)/6−311G(d,p)+ZPE*0.95 level. The major products of HCHO + CH 3C(O)CH 2CH 2OH predicted for the title reaction in the presence of O 2 and NO are in agreement with those of similar reactions of unsaturated alcohols with OH radical. 相似文献
8.
In this study, clofibric acid (CA) degraded by the electron beam (EB) irradiation was investigated at CA initial concentration of 10 mg L?1. Results showed that more than 90% CA degradation is achieved at 0.5 kGy. The acid conditions (pH 3.00) and the addition of N2 remarkably improved the CA degradation efficiency. The addition of CO32?, HCO3? anions and H2O2 reduced the CA degradation efficiency. It showed that ·H had a primary role to play in the EB degradation of CA. The determination of byproducts showed hydrosilylation reaction of CA molecules. The byproducts were clofibric acid, chlorophenol, phenol, hydroquinone, benzoquinone and dihydroxybenzene. These results suggested that electron beam irradiation (EBI) can be used to eliminate CA. 相似文献
9.
Cyanidin-3- O-xylosylrutinoside (cya-3- O-xylrut), a major pigment in Schizandra chinensis Baillon, was effectively removed by gamma irradiation of greater than 2 kGy, whereas quercetin, the most abundant of the flavonoids and has anti-inflammatory and anti-allergic effects, could be generated by degradation of cya-3- O-xylrut. In the present study, we investigated the effect of combination treatment of gamma irradiation and hydrogen peroxide (H 2O 2) on the formation of quercetin through the degradation of cya-3- O-xylrut. Cya-3- O-xylrut was significantly degraded (~93%) by gamma irradiation at 2 kGy and it was completely removed by a combination treatment (0.2% H 2O 2 and 2 kGy gamma ray). The formation of quercetin was significantly appeared at 2 kGy of gamma ray, together with disappearance of cya-3- O-xylrut. The quercetin formation by gamma ray is 3.2 μg/ml and combination treatment is 7.7 μg/ml. Therefore, the combination treatment of H 2O 2 and gamma ray is more effective to convert cya-3- O-xylrut into quercetin than gamma irradiation only. In conclusion, gamma ray combined with H 2O 2 would be a promising tool for bio-conversion of organic compounds. 相似文献
10.
Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the samples were stored for 14 days at 4 °C. O 2 levels in the packages of fresh-cut Iceberg lettuce decreased and CO 2 levels increased with increasing radiation dose, suggesting that irradiation increased respiration rates of lettuce. Tissue browning of irradiated cut lettuce was less severe than that of non-irradiated, probably due to the lower O 2 levels in the packages. However, samples irradiated at 3 and 4 kGy had lower maximum force and more severe sogginess than the non-irradiated control. In addition, ascorbic acid content of irradiated lettuce was 22–40% lower than the non-irradiated samples after 14 days of storage. The visual appearance of spinach was not affected by irradiation even at a dose of 4 kGy. Consumer acceptance suggested that more people would dislike and would not buy spinach that was treated at 3 and 4 kGy as compared to the non-irradiated sample. Overall, irradiation at doses of 1 and 2 kGy may be employed to enhance microbial safety of fresh-cut Iceberg lettuce and spinach while maintaining quality. 相似文献
11.
Thermal durability of CoSb 3 in vacuum, helium and air was investigated over the temperature range of 20–850 °C. A scanning electron microscope (SEM)
and X-ray powder diffraction technique were used to investigate the microstructure and to carry out the phase analysis of
the degradation products. The analysis of a non-isothermal and isothermal decomposition and oxidation of the CoSb 3 powders and polycrystalline samples were performed using simultaneous TG/DTA technique. More detailed studies were carried
out on the oxidation in the temperature range 400–600 °C. It was established that the decomposition products are CoSb 2 and a volatile antimony. In case of oxidation a complex three-layered scale is formed, consisting of CoSb 2O 4, CoSb 2O 6 and Sb 2O 4 layers. Both the decomposition and the oxidation kinetics are determined by a diffusion through the growing layers of products.
The electrical resistivity and Seebeck coefficient measurements have been also performed on pure and oxidized samples, which
showed a large influence of the oxidation on the electrical properties. 相似文献
12.
The effect of stage number of multistage AC gliding arc discharge reactors on the process performance of the combined reforming
and partial oxidation of simulated CO 2-containing natural gas having a CH 4:C 2H 6:C 3H 8:CO 2 molar ratio of 70:5:5:20 was investigated. For the experiments with partial oxidation, either pure oxygen or air was used
as the oxygen source with a fixed hydrocarbon-to-oxygen molar ratio of 2/1. Without partial oxidation at a constant feed flow
rate, all conversions of hydrocarbons, except CO 2, greatly increased with increasing number of stages from 1 to 3; but beyond 3 stages, the reactant conversions remained almost
unchanged. However, for a constant residence time, only C 3H 8 conversion gradually increased, whereas the conversions of the other reactants remained almost unchanged. The addition of
oxygen was found to significantly enhance the process performance of natural gas reforming. The utilization of air as an oxygen
source showed a superior process performance to pure oxygen in terms of reactant conversion and desired product selectivity.
The optimum energy consumption of 12.05 × 10 24 eV per mole of reactants converted and 9.65 × 10 24 eV per mole of hydrogen produced was obtained using air as an oxygen source and 3 stages of plasma reactors at a constant
residence time of 4.38 s. 相似文献
13.
Thermal decomposition of precursors for In 2S 3 thin films obtained by drying aqueous solutions of InCl 3 and SC(NH 2) 2 at the In:S molar ratios of 1:3 ( 1) and 1:6 ( 2) was monitored by simultaneous TG/DTA/EGA-FTIR measurements in the dynamic 80%Ar + 20%O 2 atmosphere. XRD and FTIR were used to identify the dried precursors and products of the thermal decomposition. The precursors
1 and 2 are complex compounds, while in 2 free SC(NH 2) 2 is also present. The thermal degradation of 1 and 2 in the temperature range of 30–900 °C consists of four mass loss steps, the total mass loss being 89.1 and 78.5%, respectively.
According to XRD, In 2S 3 is formed below 300 °C, crystalline In 2.24(NCN) 3 is detected only in 1 above 520 °C and In 2O 3 is the final decomposition product at 900 °C. The gaseous species evolved include CS 2, NH 3, H 2NCN, HNCS, which upon oxidation yield also COS, SO 2, HCN and CO 2. 相似文献
14.
The catalytic activity of dioxo-molybdenum(VI)-dichloro[4,4′-dicarboxylato-2,2′-bipyridine] covalently anchored through the
carboxylate function to the surface of TiO 2 has been tested for the oxidative degradation of 1-chloro-4-ethylbenzene in MeCN solution under argon and UV irradiation
(λ = 254 nm). After 4–5 h of photochemical reaction, the Mo complex was reoxidized in the presence of O 2 in the dark, and then the reaction was continued under argon. The reaction proceeds by the intermediate formation of 4′-chloroacetophenone
that undergoes further decomposition to chlorobenzene, plus small amounts of oxygen-containing organochlorine compounds, CO 2 and H 2O. Similar results were obtained for the decomposition of 4′-chloroacetophenone under the same conditions, which also gave
chlorobenzene as one of the main products. The ratio of [final product]/[Mo complex] increases during the decomposition of
1-chloro-4-ethylbenzene (up to 350–400% for 30–35 h of reaction), which provides evidence of a catalytic process. The probable
photochemical reactions are discussed. 相似文献
15.
The decomposition by electron beam (EB) irradiation of 1-chloronaphthalene in different gas matrices (air, N 2) was studied. Over 80% 1-chloronaphthalene was decomposed in air at 58 kGy dose when the initial concentration of 1-chloronaphthalene was 12–30 mg/Nm 3. Over 50% 1-chloronaphthalene was decomposed in nitrogen when the initial concentration of 1-chloronaphthalene was 15–42 mg/Nm 3. 相似文献
16.
The decomposition of volatile organic compounds (VOCs) using a pilot system of electron beam (EB)–catalyst coupling was investigated. Two aromatic VOCs, toluene (1800 ppmC) and o-xylene (1500 ppmC), were irradiated with a dose range of 0–10 kGy at room temperature. The removal efficiencies for toluene and o-xylene were 92.4% and 94.5%, respectively, under a 10 kGy absorbed dose condition, which were higher than the results of 45.7% and 52.3% when EB-only was used, respectively. The CO 2 selectivity approached 100% for both toluene and o-xylene using the EB-catalyst coupling system, while the concentrations of O 3 formed were 0.02 ppm (toluene) and 0.003 ppm (o-xylene) at 10 kGy. The aerosol concentration was also measured as 43.2 μg/m 3 (toluene) and 53.4 μg/m 3 (o-xylene) at 10 kGy absorbed dose. 相似文献
17.
An FT‐IR kinetic and product study of the Br‐atom‐initiated oxidation of dimethyl sulfide (DMS) has been performed in a large‐volume reaction chamber at 298 K and 1000‐mbar total pressure as a function of the bath gas composition (N 2 + O 2). In the kinetic investigations using the relative kinetic method, considerable scatter was observed between individual determinations of the rate coefficient, suggesting the possibility of interference from secondary chemistry in the reaction system involving dimethyl sulfoxide (DMSO) formation. Despite the experimental difficulties, an overall bimolecular rate coefficient for the reaction of Br atoms with DMS under atmospheric conditions at 298 K of ≤1 × 10 −13 cm 3 molecule −1 s −1 can be deduced. The major sulfur products observed included SO 2, CH 3SBr, and DMSO. The kinetic observations in combination with the product studies under the conditions employed are consistent with rapid addition of Br atoms to DMS forming an adduct that mainly re‐forms reactants but can also decompose unimolecularly to form CH 3SBr and CH 3 radicals. The observed formation of DMSO is attributed to reactions of BrO radicals with DMS rather than reaction of the Br–DMS adduct with O 2 as has been previously speculated and is thought to be responsible for the variability of the measured rate coefficient. The reaction CH 3O 2 + Br → BrO + CH 3O is postulated as the source of BrO radicals. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 883–893, 1999 相似文献
18.
Novel visible-light-activated In 2O 3–CaIn 2O 4 photocatalysts were developed in this paper through a sol–gel method. The photocatalytic activities of In 2O 3–CaIn 2O 4 composite photocatalysts were investigated based on the decomposition of methyl orange under visible light irradiation (λ > 400 nm).
The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive
spectrum (EDS), X-ray photoelectron spectroscopy (XPS) and UV–vis diffused reflectance spectroscopy (DRS). The results revealed
that the In 2O 3–CaIn 2O 4 composite samples with different In 2O 3 and CaIn 2O 4 content can be obtained by controlling the synthesis temperature, and the composite photocatalysts extended the light absorption
spectrum toward the visible region. The photocatalytic tests indicated that the composite samples demonstrated high visible-light
activity for decomposition of methyl orange. The significant enhancement in the In 2O 3–CaIn 2O 4 photo-activity under visible light irradiation can be ascribed to the efficient separation of photo-generated carriers in
the In 2O 3 and CaIn 2O 4 coupling semiconductors. 相似文献
19.
The chemical tropospheric dimethyl sulfide (DMS, CH 3SCH 3) degradation involves several steps highly dependent on the environmental conditions. So, intensive efforts have been devoted during the last years to enhance the understanding of the DMS oxidation mechanism under different conditions. The reaction of DMS with OH is considered to be the most relevant process that initiates the whole oxidation process. The experimental observations have been explained by a two‐channel mechanism consisting of a H‐abstraction process leading to CH 3S(O)CH 3 and HO 2 and an addition reaction leading to the DMS · OH adduct. In the presence of O 2, the DMS · OH adduct is competitively scavenged increasing the contribution of the addition channel to the overall DMS oxidation. Recent experimental measurements have determined from a global fit that the rate constant of this scavenging process is independent of pressure and temperature but this rate constant cannot be directly measured. In this article, a variational transition‐state theory calculation of the low‐ and high‐pressure rate constants for the reaction between DMS · OH and O 2 has been carried out as a function of temperature. Our proposal is that the slight temperature dependence of the scavenging rate constant can only be explained if the H‐abstraction bottleneck is preceded by a dynamical bottleneck corresponding to the association process between the DMS · OH adduct and the O 2 molecule. The agreement between the low‐pressure and high‐pressure rate constants confirms the experimental observations. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
20.
Spherical Li[Ni 1/3Co 1/3Mn 1/3]O 2 cathode materials with different microstructure have been prepared by a continuous carbonate co-precipitation method using
LiOH⋅H 2O, Li 2CO 3, CH 3COOLi⋅2H 2O and LiNO 3 as lithium source. The effects of Li source on the physical and electrochemical properties of Li[Ni 1/3Co 1/3Mn 1/3]O 2 are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurements. The results
show that the morphology, tap density and high rate cycling performance of Li[Ni 1/3Co 1/3Mn 1/3]O 2 spherical particles are strongly affected by Li source. Among the four Li sources used in this study, LiOH⋅H 2O is beneficial to enhance the tap density of Li[Ni 1/3Co 1/3Mn 1/3]O 2, and the tap density of as-prepared sample reaches 2.32 g cm −3. Meanwhile, Li 2CO 3 is preferable when preparing the Li[Ni 1/3Co 1/3Mn 1/3]O 2 with high rate cycling performance, upon extended cycling at 1 and 5C rates, 97.5% and 92% of the initial discharge capacity
can be maintained after 100 cycles. 相似文献
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