Efficiency Of NO Research Articles

Production of Oxidant through Catalytic H2O2 Decomposition for NO Treatment

The NO oxidation process has been applied to improve a removal efficiency of NO included in exhaust gas. In this study, to produce a dry oxidant for the NO oxidation process, the catalytic H2O2 decomposition method was proposed. A variety of the heterogeneous solid-acidic Mn-based catalysts were prepared for the catalytic H2O2 decomposition and the effect of their physico-chemical properties on the catalytic H2O2 decomposition was investigated. The results of this study showed that the acidic sites of the Mn-based catalysts have an influence on the catalytic H2O2 decomposition. The Mn-based catalyst having the abundant acidic sites within the wide temperature range in NH3-TPD shows the best performance for the catalytic H2O2 decomposition. Therefore, the NO oxidation efficiency, using the dry oxidant produced by the H2O2 decomposition over the Mn-based catalyst having the abundant acidic properties under the wide temperature range, was higher than the others. As a remarkable result, the best performances in the catalytic H2O2 decomposition and NO oxidation were shown when the Mn-based Fe2O3 support catalyst containing K component was used for the catalytic H2O2 decomposition.

Density functionalized [RuII(NO)(Salen)(Cl)] complex: Computational photodynamics and in vitro anticancer facets

Photodynamic therapy (PDT) is a treatment that uses photosensitizing agents to kill cancer cells. Scientific community has been eager for decades to design an efficient PDT drug. Under such purview, the current report deals with the computational photodynamic behavior of ruthenium(II) nitrosyl complex containing N, N'-salicyldehyde-ethylenediimine (SalenH2), the synthesis and X-ray crystallography of which is already known [Ref. 38,39]. Gaussian 09W software package was employed to carry out the density functional (DFT) studies. DFT calculations with Becke-3–Lee–Yang–Parr (B3LYP)/Los Alamos National Laboratory 2 Double Z (LanL2DZ) specified for Ru atom and B3LYP/6-31G(d,p) combination for all other atoms were used using effective core potential method. Both, the ground and excited states of the complex were evolved. Some known photosensitizers were compared with the target complex. Pthalocyanine and porphyrin derivatives were the compounds selected for the respective comparative study. It is suggested that effective photoactivity was found due to the presence of ruthenium core in the model complex. In addition to the evaluation of theoretical aspects in vitro anticancer aspects against COLO-205 human cancer cells have also been carried out with regard to the complex. More emphasis was laid to extrapolate DFT to depict the chemical power of the target compound to release nitric oxide. A promising visible light triggered nitric oxide releasing power of the compound has been inferred. In vitro antiproliferative studies of [RuCl3(PPh3)3] and [Ru(NO)(Salen)(Cl)] have revealed the model complex as an excellent anticancer agent. From IC50 values of 40.031mg/mL in former and of 9.74mg/mL in latter, it is established that latter bears more anticancer potentiality. From overall study the DFT based structural elucidation and the efficiency of NO, Ru and Salen co-ligands has shown promising drug delivery property and a good candidacy for both chemotherapy as well as light therapy.

Study on the mechanism of NO removal by plasma-adsorption catalytic process

An integrated technology, the non-thermal plasma (NTP) combined with bamboo charcoal (BC) adsorption catalytic, was used for the removal of NO. It was found that the BC extended gas residence time and acted as a scavenger of O2. The NO removal rate showed an increasing trend with increasing input voltage, reaching the maximum at 80V, and then decreased at higher applied input voltage. The removal of NO was mainly through the reduction of NO to N2. The presence of O2 and SO2 remarkably inhibited the removal of NO. Approximately 86.2% of NO was removed in the absence of O2, whereas the removal efficiency of NO was 74.0% in the presence of 8% O2. The adsorbents were characterized by SEM, XRD, N2 adsorption-desorption and XPS to determine the pore and surface chemistry structures. Results showed that the BC after plasma treatment had a large number of small cavities. The plasma treatment increased the BET surface area and introduced oxygen functional groups.

High Selectivity of Visible-Light-Driven La-doped TiO2 Photocatalysts for NO Removal

Semiconductors mediated by rare earth metals (REMs) have attracted attention with regard to the degradation of pollutants. In order to enhance the visible response of TiO2, La-doped TiO2 (La-TO) photocatalysts with visible-light-driven capacity for NO removal were successfully synthesized in this study via a facile sol-gel method followed by calcination. A series of La-TiO2 samples with differing weight ratios were evaluated for their photocatalytic performances. It was found that 3% La integrated with TiO2 (in mass ratio) could enhance the removal efficiency of NO (up to 32%) under solar light, which is more than twice that seen with pure TiO2. The resulting products were characterized by a series of techniques, such as XRD, FTIR, UV-vis DRS, BET and (photo)electrochemical analysis. The results indicated that La-doped TiO2 can harvest visible light due to the relatively narrow band gap (from 2.98 to 2.75 eV). More importantly, La dopant improved electron-hole separation and suppressed charge carrier recombination, due to the synergistic effect. Furthermore, La-doped TiO2 increased the photo-oxidation efficiency of the transformation from NO to NO3–, owing to inhibition of the production of intermediate NO2 (0.02%). To the best of our knowledge, this study is the first time that La-doped TiO2 has been used to eliminate NO (at the ppb level) in the atmosphere. This study provides a facile and controllable route to fabricate La-TO photocatalyst for NO abatement with high selectivity of NO2 under visible light.

Operation of a Three-Electrode Reactor With Different Electrode Bias Potential Configurations

The three-electrode plasma reactor for the treatment of polluted gases combines a dielectric-barrier discharge with a remote third electrode, designed to enhance streamer propagation in a relatively large region. In this paper, experimental studies of the electrical magnitudes of the discharge for different electrode bias voltage configurations are presented. Also, the Laplacian electric field distribution in the interelectrode gap is calculated for each configuration. The degradation efficiency of NO in an N2 atmosphere for the different configurations is also reported. It is found that the discharge is generated only for that electrode bias configuration for which the external electric field promotes the streamer propagation across the electrode gap. Also, for a triggered discharge, the reactor efficiency for the removal of NO changes with the different electrode bias configurations. This result can be explained in terms of the electric field intensity. The configuration with higher external electric field improves the number of streamers propagating in the interelectrode gap so that more reactive species generated in the streamers are effectively entrained in the gas flow to be treated.

A numerical investigation of reactive air pollutant dispersion in urban street canyons with tree planting

Vegetation acts as a momentum and thermal sink, affecting the mixing of species and temperature-dependent constants of reaction rates. Numerical simulations were performed to investigate the effects of vegetation on the dispersion of reactive pollutants using a computational fluid dynamic (CFD) model coupled with NO-NO2-O3 photochemistry. Moreover, characteristics of temperature and flow fields were analyzed for different aspect ratios and leaf area densities. The results showed that flow is reversed in the presence of trees, and it enhances as leaf area density (LAD) increases; additionally, vegetation creates downward and vortex flows. The results also revealed that the dispersion of nitrogen oxides is influenced by the flow patterns; nevertheless, chemical reactions are significant for the dispersion of ozone. In addition, the vegetation is observed to weaken ventilation efficiency of NO and NO2; however, ventilation efficiency of O3 improves in LAD = 0.5 and 1.0. Aspect ratios and leaf area densities are also found to interact with each other; consequently, the optimum LAD is different for each aspect ratio. The larger regions with maximum concentrations of nitrogen oxides at the height of 2 m for aspect ratios of 0.5, 1.0, and 2.0 correspond to LAD = 2.0, 1.5, and 1.0, respectively. Furthermore, vegetation as compared to tree-free environment, mostly leads to a better chemical equilibrium.

Photocatalytic oxidation of NO over TiO2-Graphene catalyst by UV/H2O2 process and enhanced mechanism analysis

This study aimed at investigating the photocatalytic oxidation (PCO) of NO under the UV/H2O2 system over a series of TiO2-Graphene (TiO2-GR) catalysts, which was able to dramatically improve the PCO efficiency of NO compared with pure TiO2, and the NO oxidative product was the stable nitrate. The electronic interfacial interaction between GR and TiO2 resulted in a negative shift of the CB of TiO2 evidenced by MS. The excellent conductivity of GR suppressed e−/h+ pairs recombination effectively, and GR as a kind of dispersant reduced the size of TiO2, increased the active sites. These advantages offered e− and h+ more opportunities to participate in PCO of NO, resulting in significant improvement of the PCO efficiency. The effects of the active species involved in the photocatalytic process were also examined. Moreover, different tests were designed to further confirm the improved mechanism. Further investigations showed that the h+ could oxidize NO directly.

<italic>In situ </italic>synthesis, band structure analysis and of visible light photocatalysis enhancement mechanism of K-doped C<sub>3</sub>N<sub>4</sub>

For the past few years, air quality has surged to worldwide attention. For NO x purification, semiconductor photocatlysis as a green technology that could use sunlight to purify air pollutants, provides an attractive alternative to decrease pollution. Recently, polymeric graphitic carbon nitride (g-C 3 N 4 ) materials have drawn intensive attention because of its metal-free and high-hardness features, reliable chemical inertness, thermal stability, as well as its versatile optical, electrochemical, and efficient photocatalytic properties. But pure g-C 3 N 4 suffers from rapid recombination of photo- generated electron-hole pairs resulting in low photocatalytic activity. Thus, several coping modifying methods were employed to improve the photocatalytic performance of g-C 3 N 4 . The present work developed a facile in situ method to construct novel k-doped g-C 3 N 4 (CN-K) structure with molecular composite precursors. In this work, the samples were prepared via pyrolysis of thiourea and a certain amount of KI as the potassium source in a muffle furnace. Different mass ratio (1%, 3%, 5%, 10%) of K-doping g-C 3 N 4 samples were prepared by changing the amount of KI. The as-prepared samples were systematically characterized by XRD, SEM, TEM, XPS, BET, UV-vis DRS and PL. Material studio was used to simulated the crystalline structure of potassium doped g-C 3 N 4 . The bond structure of as-prepared samples can be theoretical calculation by DFT theoretical calculation. Both the experimental and theoretical calculation results indicated that potassium ion which were formed chemical bond with nitrogen existed in the interlayer of g-C 3 N 4 . The modified catalyst exhibited outstanding photocatalytic activity and photochemical stability towards degradation of NO at ppb-level under visible light irradiation. The superior activity can be ascribed to the significant function of potassium ion worked on morphological structure, band gap and electronic-hole recombination of as prepared samples. Firstly, evidenced by valence band XPS and DFT theoretical calculation, potassium doping has the function of modifying band-gap, making for down-shift both conduction band and valence band, however, The extent of the conduction band down shifting more than the valence band, shortening down the optical band gap more while making a significant enhancement of the solar light response range, thus the absorption capacity of as prepared samples strengthen significantly. Secondly, the separation efficiency of photon-generated carriers increased with potassium doped in the interlayer of g-C 3 N 4 verified by room temperature PL spectra. Thirdly, the in situ K-doped g-C 3 N 4 showed higher oxidation capacity of photo-induced holes for degradating NO, ascribed to a more positive valence band. Integrated three factors, purification efficiency of NO has been significantly improved. This work could provide a new perspective for modification of photocatalyst with alkali metals and mechanism understanding of NO degradation.

Influence of the biogas reburning for reducing nitric oxide emissions in an alundum-tube reactor

The experimental study on reburning reduction reaction between biogas and NO is very important in de-NOx technology. The reburning experiments by the simulated biogas with different operation variables have been performed in an alundum-tube reactor. Results showed that the uppermost constituent in NO-reduction was CH4, H2 second, and NO-reduction by CO in biogas reburning was negligible at the same conditions. In the condition of oxygen-poor, H2 could promote CH4 oxidation and enhance the concentration of CH3 radicals, thereby increasing the reduction efficiency of NO accordingly. At the same temperature, with the increase of stoichiometric ratio, it would increase O radicals and decrease NO reduction efficiency. With the increase of reaction temperature, the reduction efficiency behaved a trend of first increased then decreased at the same stoichiometric ratio, and obtained the maximum value 51.38% at the condition of 1200 °C and λ = 0.6. Additionally, increasing the NO input concentration also could improve the reduction efficiency under the condition of fuel-rich.

Synergistic Effect of Mediated Electrochemical Reduction and Mediated Electrochemical Oxidation on NO Removal by Electro-Scrubbing

A combined MER (mediated electrochemical reduction) and MEO (mediated electrochemical oxidation) approach was examined for the first time for the efficient removal of NO by electro-scrubbing. The generation of a mediator (Ni(I) from Ni(II)(CN)42− in 9 M KOH) by electrochemical reduction was identified by the changes in the ORP value and potentiometric titration. The Ni(I) formation found to be 9% (4.3 mM) in 2 h electrolysis, which is decreased to 1.83 mM (4%) during addition of NO demonstrates NO removal occurred. The MER of NO at the cathodic half-cell by electro-scrubbing revealed the formation of NH3 and N2. The reductive removal efficiency of NO was almost 100% up to a gas flow rate of 0.25 g min−1. At the anodic half-cell, the Co(III) mediator from Co(II)SO4 in 5 M H2SO4 was generated electrochemically with concomitant conversion of NO to NO3− in the solution phase with a removal efficiency of 28%. The combination of MEO and MER with electro-scrubbing demonstrates 97% removal efficiency of NO up to 0.5 g min−1. The combined removal approach is more suitable for high concentrated NO with energy efficiency of 0.99 g/kWh compared to the individual MEO (0.221 g/kWh) and MER (0.769 g/kWh) approaches.

介质阻挡放电烟气脱硝的实验研究

研究分析了介质阻挡放电低温等离子技术脱除NO机理、NO初始浓度和氧气含量对NO脱除效率的影响。实验结果表明，在20 KV时，O2含量从0%增加到8%，NO在各个电压下的脱除效率均下降，介质阻挡放电脱除NO的效率也由60%下降到33.8%。随着NO初始浓度的增加，NO脱除效率也由83%下降到33%。NO初始浓度的提高、O2含量的增加都会导致NO的脱除率的明显降低。 The influence of NO concentration and oxygen content on the removal efficiency of NO by low temperature plasma technique with dielectric barrier discharge was studied and analyzed. NO removal efficiency was analyzed. Experimental results show that at 20 KV, O2 content increased from 0% to 8%, NO removal efficiency at each voltage decreased, and NO removal efficiency of dielectric barrier discharges dropped from 60% to 33.8%. With NO initial concentration increases, NO removal efficiency has dropped from 83% to 33%. NO initial concentration of O2 and removal of content increase will result in the decrease of NO rate significantly.

NO 산화를 위한 Mn계 촉매상 과산화수소 분해를 이용한 건식산화제 생성

The NO oxidation process has been applied to improve a removal efficiency of NO included in exhaust gas. In this study, to produce a dry oxidant for the NO oxidation process, the catalytic H2O2 decomposition method was proposed. A variety of the heterogeneous solid-acidic Mn-based catalysts were prepared for the catalytic H2O2 decomposition and the effect of their physico-chemical properties on the catalytic H2O2 decomposition were investigated. The results of this study showed that the acidic sites of the Mn-based catalysts has an influence on the catalytic H2O2 decomposition. The Mn-based catalyst having the abundant acidic sites within the wide temperature range in NH3-TPD shows the best performance for the catalytic H2O2 decom- position. Therefore, the NO oxidation efficiency, using the dry oxidant produced by the H2O2 decomposition over the Mn-based catalyst having the abundant acidic properties under the wide temperature range, was higher than the others. As a remarkable result, the best performances in the catalytic H2O2 decomposition and NO oxidation was shown when the Mn-based Fe2O3 support catalyst containing K component was used for the catalytic H2O2 decomposition.

Simultaneous photocatalytic elimination of gaseous NO and SO2 in a BiOI/Al2O3-padded trickling scrubber under visible light

The simultaneous photocatalytic elimination of NO and SO2 was achieved in a BiOI/Al2O3-padded trickling scrubber under visible light. The BiOI/Al2O3 composites, in which nanostructured BiOI was well dispersed on the surface of Al2O3, were successfully synthesized through solvothermal method. The prepared BiOI/Al2O3 was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectra (DRS). The elimination of NO and SO2 was studied in a BiOI/Al2O3 trickling scrubber. It was found that the removal efficiency of NO and SO2 could reach 100% in photocatalytic BiOI/Al2O3-padded trickling scrubber, demonstrating that the present method performs well for simultaneous denitrification and desulfurization. The high removal efficiency for NO and SO2 was attributed to the enhanced gas absorption of BiOI/Al2O3 composites and the generation of reactive OH under visible-light irradiation in the system. The involvement of OH in oxidizing NO and SO2 was examined by determining the photocurrent of BiOI/Al2O3 and removal rates using different scavengers. Ion chromatography (IC) analysis identified that NO3− and SO42− were main products, and the mass balances analysis for N and S in scrubbing solution indicated that NO and SO2 were completely oxidized to be NO3− and SO42−. Most importantly, this BiOI/Al2O3 wet photocatalytic scrubber retained their simultaneous desulfurization and denitrification efficiencies for long-term repetitive batch runs, indicating the stable photocatalytic process.

An assessment of low temperature NOx adsorbers for cold-start NOx control on diesel engines

Fresh and thermally aged laboratory samples of several low temperature NOx adsorber (LTNA) formulations were evaluated for low temperature NOx storage and release under lean conditions to assess their potential for treating the cold-start NOx emissions on diesel engines before the SCR system becomes operational. Steady-state tests were used to determine the NOx storage capacity as a function of temperature and to determine the minimum temperature for purging the LTNA of stored NOx. The samples were also evaluated on a transient test performed on the reactor that simulated the thermal environment during the first two phases of the light-duty Federal Test Procedure (FTP-75) followed by a Supplemental FTP (US06) test. The Pt-rich LTNAs exhibited low NOx storage performance during the initial 200s of this transient test due to low storage efficiency of NO and weak NO oxidation capability. A Pd-rich formulation provided efficient storage of NO and C2H4 on the transient test and released most of the stored NO by 350°C. The presence of C2H4 improved its NOx storage performance after thermal aging. SO2 poisoned the storage of NO2 as nitrates at 170°C, but the storage of NO as nitrites at lower temperatures (e.g., 90–140°C) was more robust to the SO2. A lean desulfation at 750°C recovered some of the storage performance. The Pd-rich LTNA performed best when highly oxidized. This catalyst demonstrated a gradual loss of NOx storage performance when evaluated on consecutive lean transient tests. This was attributed to the gradual reduction of the palladium oxide from reacting with the feedgas NO and C2H4 to form NO2 and CO at temperatures near 90°C. Methane oxidation was used to probe the oxidation state of the palladium oxide and confirmed that the palladium oxide was partially reduced after only two lean transient tests.

NH3-activated carbon nanofibers for low-concentration NO removal at room temperature

Nitrogen-doped carbon nanofibers (NCNFs) were prepared by activating electrospun carbon nanofibers using NH3 as activating agent at different temperatures. NCNFs with various contents of nitrogen were used as adsorbents and catalysts for low-concentration NO removal at room temperature. The NO removal efficiency over NCNFs was far above that over porous carbon nanofibers obtained by steam-activation, suggesting that NCNFs are efficient catalysts for low-concentration NO removal at room temperature. A maximum of 64.5% removal efficiency for NO was acquired at NO initial concentration of 20ppm and 21vol.% of O2 at room temperature.

Simultaneous removal of SO2 and NOx with ammonia combined with gas-phase oxidation of NO using ozone

A process for simultaneous desulfurization and denitrification was proposed, which was made up of ozone as the oxidizing agent for NO and ammonia solution as absorbent. The results showed that the presence of SO2 and the concentration changes of NO and SO2 have little impact on the oxidation of NO, the oxidation efficiency of NO can achieve over 90% when the molar ratio of O3/NO is 1.0. The presence of NOx had little effects on the absorption of SO2, an appropriate increase of SO2 concentration was favorable to the NOx absorption. The removal efficiency of SO2 and NOx reached 99.34% and 90.01% at pH 10, flow rate 0.95 Nm3/h, n[O3]/n[NO] 1.0, initial SO2 concentration 2000 mg/Nm3, initial NO concentration 200 mg/Nm3, ammonia concentration 0.3%, oxygen content of the simulated flue gas 12%, oxidation reaction temperature 423K and absorption reaction temperature 298K in the experimental system.

Activated carbon fibers loaded with MnO2 for removing NO at room temperature

Abstract MnO 2 loaded on activated carbon fibers (MnO 2 @ACF) were successfully prepared using co-precipitation methods, the as-prepared MnO 2 @ACF were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and N 2 adsorption/desorption analysis. The results showed that MnO 2 particles were highly dispersed with a strong interaction between MnO 2 particles and ACFs. MnO 2 loaded on ACF can promote the catalytic oxidation efficiency of NO into NO 2 remarkably, the loaded amount of MnO 2 has an obvious effect on the NO oxidation efficiency over MnO 2 @ACF. The optimal amount of MnO 2 for MnO 2 @ACF is 3.64 wt.%, and the oxidation efficiency of NO was increased from 20.1% over A15 to 30.6% over MnO 2 @ACF.

Simultaneous Absorption of SO<sub>2</sub> and NO Using Sodium Chlorate/Urea Absorbent in a Rotating Packed Bed

In this work, simultaneous absorption of SO2and NO from N2-NO-SO2simulated flue gas using sodium chlorate as the additive and urea as the reductant was investigated experimentally in a rotating packed bed. In RPB, various rotational speeds, gas flow rates and liquid flow rates were studied by means of the removal efficiency of SO2and NO. The experimental results showed that the removal efficiency of SO2was higher than 99.00% under various experimental conditions and, at the same time, the removal efficiency of NO exhibited different results under various experimental conditions. The simultaneous NO removal efficiency of 82.45% and the SO2removal efficiency of 99.49% could be obtained under the N2flow rate of 0.5 m3/h, SO2flow rate of 6 mL/min, the NO flow rate of 4 mL/min, the rotational speed of 460 rpm and the absorbent flow rate of 40 L/h.

Experiment on Simultaneous Absorption of NO and SO2 from Sintering Flue Gas by Oxidizing Agents of KMnO4/NaClO

Abstract A complex oxidizing agent combination made up of KMnO4 and NaClO was used to investigate the simultaneous absorption of NO and SO2 from sintering flue gas in a spray absorption tower on a laboratory scale. The effects of various operating parameters, i.e. initial gas temperature (Tg), initial solution pH, molar ratio of NaClO/KMnO4 (M), initial NO inlet concentration (CN) and SO2 initial inlet concentration (CS), were systematically investigated in the experiments. The results showed that the removal efficiency of SO2 was slightly affected by the reaction conditions and remained stable above 98%; however, the removal efficiency of NO was significantly influenced. It presented different trends with the reaction condition changed. The most optimal experimental conditions for simultaneous removal of NO and SO2 were found to be initial solution pH=5.5, Tg=50°C, M=3; in this case the average removal efficiencies of NO and SO2 could reach 98.8 and 70.9%, respectively.

Hybrid TiO2 based plasma-catalytic reactors for the removal of hazardous gasses

The paper deals with the removal of hazardous gasses by hybrid plasma-catalytic reactors. Coaxial dielectric barrier discharge (DBD) reactor was used for the generation of plasma and a layer of catalytic TiO2 powder was pressed on the inner wall of the plasma reactor to allow direct contact between the plasma and catalyst. The reactor was used for the oxidation of NO or SO2 in the mixture with 10% O2 and N2 balance. In some cases, H2O vapor or CO2 was added to the mixture to investigate the effect of these exhaust gas constituents on the NO removal. The presence of TiO2 coating in the reactor zone increased the oxidation efficiency for both treated gasses but was more pronounced in the case of SO2. There were also some differences regarding the effect of temperature and humidity. It was necessary to use higher temperatures to increase the removal efficiency of NO by TiO2 catalyst compared to SO2. In humid conditions, the removal of NO was further increased by the TiO2 catalyst while the enhancement of SO2 removal by catalyst was not detectable.