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Abstract
The reactivitys of toluene degradation were investigated at room temperature under atmospheric pressure by using a non-thermal plasma reactor loaded with SiO2, Al2O3 and NiO/Al2O3. The different reactivities on these catalysts may originate from their dielectric constant, toluene adsorption and ozone decomposition abilities on their surface. In addition, in-situ infrared spectrum technology was used to study adsorption species on catalyst surface during the toluene degradation. The results showed that, within a certain range, the degradation rate of toluene increased along with the energy density, dielectric constant, adsorption and the ozone-decomposing ability. Toluene adsorption species on the catalyst surface played important roles on toluene degradation. The toluene degradation occurred in the vapor phase if SiO2 was loaded in the discharge region. However, when Al2O3 or NiO/Al2O3 was loaded, the oxidation of toluene to benzoic mainly occurred on the catalyst surface, which was the key step of toluene degradation, and the accumulation of benzoic acid on the active sites would decrease the catalyst reactivity.
... The band of the toluene adsorption appeared on all the catalysts: 1392, 1460, 1495 and 1608 cm −1 characteristics of aromatic ring C=C stretching vibration (Li et al., 2007); 2879, 2928 cm −1 characteristics of C-H vibrations of methyl (Maira et al., 2001;Eby et al., 2012); 3031 cm −1 characteristic of C-H vibration of aromatic ring (Maira et al., 2001). Also, the new adsorption bands at 1120, assigned to terpene OH stretching (Das et al., 2014), and 1167, assigned to ester C-O stretching (Long et al., 2011;Yang et al., 2013), appeared on the surface of catalyst loaded with Ag. This indicates that the toluene oxidation on the catalyst surface was improved due to the Ag introduction. ...
Experimental study the degradation efficiency of toluene by bipolar corona discharge coupled with TiO2 photocatalysis. Bipolar corona discharge can degrade the toluene efficiently and rapidly, the final products are mainly carbon dioxide and water. Toluene removal efficiency reduces when the initial concentration of toluene increasing, while toluene removal quantity is increased. Removal of toluene decreases with the gas flow rate increasing, the removal quantity first increases and then decreases. Bipolar corona discharge and a photocatalytic coupling can inprove the degradation efficiency further. Increase of the applied voltage help to improve the removal of toluene, and also to improve the coupling effect of the photocatalyst. In optimized conditions, the removal efficiency of toluene can be more than 90%. The chemical reaction process of the toluene oxidation and the TiO2 catalysis mechanism are discussed. It is pointed out that the OH* produced by corona discharge has important significance for rapid oxidation of toluene.
Using a combination of nanoscale infrared spectroscopy (AFM-IR) and nanoscale thermal analysis (nanoTA), the composition of a complex multilayer polymer film was deconstructed. (Table 1). Using an AFM cantilever as an IR absor-bance detector, the topography of the film's cross-section is directly correlated to the corresponding infrared spectra and transition temperatures at high spatial resolution. Chemical information about the small organic inclusions (as small as 1.2 pm) is extracted within Layers 4 and 6. The nanoTA technique determined the transition temperatures of each layer of the cross-section. Not only do the two methods complement and strengthen the validity of the chemical assignments, the chemical and thermal properties can be linked to the spatial and topographic information about the same sample. The results of AFM-IR and nanoTA may be combined with findings from other techniques such as scanning electron microanalysis (SEM) to obtain a full understanding of the material.
A coaxial double dielectric barrier discharge (DBD) reactor is developed for plasma-catalytic conversion of CH4 and CO2 into syngas and other valuable products. A supported metal catalyst (Ni/Al2O3) reduced in a methane discharge is fully packed into the discharge region. The influence of the Ni/Al2O3 catalyst packed into the gas gap on the electrical characteristics of the discharge is investigated. The introduction of the catalyst pellets leads to a transition in discharge behaviour from a typical filamentary microdischarge to a combination of spatially limited microdischarges and a predominant surface discharge on the catalyst surface. It is also found that the breakdown voltage of the CH4/CO2 discharge significantly decreases when the reduced catalyst is fully packed in the discharge area. Conductive Ni active sites dispersed on the catalyst surface contribute to the expansion of the discharge and enhancement of charge transfer. In addition, plasma-catalytic dry reforming of CH4 is carried out with the reduced Ni/Al2O3 catalyst using a mixing ratio of CH4/CO2 = 1 and a total flow rate of 50 ml min−1. An increase in H2 selectivity is observed compared with dry CH4 reforming with no catalyst, while the H2/CO molar ratio significantly increases from 0.84 to 2.53 when the catalyst is present.
Three different room temperature ionic liquids (RTILs) namely protonated betaine bis(trifluromethylsulfonyl)imide ([Hbet][Tf(2)N]), N-butyl-N-methylpyrrolidinium bis(trifluromethylsulfonyl)imide (BMPyTf(2)N) and N-methyl-N-propylpiperidinium bis(trifluromethylsulfonyl)imide (MPPiTf(2)N) were synthesized and characterized by CHNS analysis, NMR and FTIR spectroscopy. Heat capacity measurements and thermogravimetric analysis of these RTILs were carried out and the results are reported in this paper.
The possibilities to identify polycarbonyl species using different CO isotopic mixtures (12C16O+13C16O and 12C16O+13C18O) are regarded. The examples concern two nickel-containing catalysts, Ni–ZSM-5 and Ni/SiO2. Ni+ ions, present in Ni–ZSM-5 reduced by CO, can coordinate up to three CO molecules each. Ni+(CO)2 dicarbonyl structures are well established by both, 12C16O+13C16O and 12C16O+13C18O isotopic mixtures. However, the 12C16O+13C18O mixture is advantageous in the determination of tricarbonyl structures. This is due to the much higher 12C16O→13C18O isotopic shift (about 100cm−1) as compared to the 12C16O→13C16O shift (ca. 50cm−1) which allows a better resolution of the different carbonyl bands. The use of 12C16O+13C18O mixtures also permits assignment of the bands due to polycarbonyl structures when CO is adsorbed on a reduced Ni/SiO2 catalyst.
KeywordsAdsorption–CO–
13C16O–
13C18O–Nickel–Ni–ZSM-5–Ni/SiO2
We have developed a new method for solid phase extraction (SPE) and preconcentration of trace amounts of cadmium and zinc using cross linked chitosan that was functionalized with 2-aminopyridine-3-carboxy acid. Analytical parameters, sample pH, effect of flow rate, sample volume, and concentration of eluent on column SPE were investigated. The effect of matrix ions on the recovery of cadmium and zinc has been investigated and were found not to interfere with preconcentration. Under the optimum experimental conditions, the preconcentration factors for Cd(II) and Zn(II) were found to be 90. The two elements were quantified via atomic absorption spectrometry. The detection limits for cadmium and zinc are 21 and 65 ng L−1, respectively. The method was evaluated by analyzing a certified reference material (NIST 1643e; water) and has been successfully applied to the analysis of cadmium and zinc in environmental water samples.
Figure
A simple and sensitive solid phase extraction method for the preconcentration of Cd(II) and Zn(II) in environmental samples using cross linked chitosan functionalized with 2-aminopyridine-3-carboxylic acid was developed. The metal ions enriched by functionalized chitosan were eluted with acid and determined by AAS.
We describe a new strategy for the in situ growth of molecular wires predicated on the synthesis of a trifunctional “primed”
contact formed from metal-carbon multiple bonds. The ruthenium-carbon π bond provides structural stability to the molecular
linkages under ambient conditions, and density functional calculations indicate the formation of an efficient conduit for
charge carriers to pass between the metal and the molecule. Moreover, the metal-carbon π bond provides a chemically reactive
site from which a conjugated molecular wire can be grown in situ through an olefin metathesis reaction.
A plasma-catalytic combined reactor system was used to decompose volatile organic compounds. Metal oxide catalysts, as well as Pt-based catalyst, were employed in the studies. The plasma treatment alone leads to the formation of high concentration of byproducts. A Pt-based catalyst, combined with plasma reactor, was helpful in minimizing the byproduct formation. The plasma reactor significantly enhances the catalytic performance. Plasma reactor, combined with Pt-based catalyst, removed more than 90% of toluene. The Pt-based catalyst completely removed the CO produced by plasma reactor. In order to determine the mechanism of the plasma treatment, the plasma reactor was replaced by ozone reactor and the results were compared with plasma-catalytic reactor. It was found that ozone plays a significant role in enhancing the catalytic activity.
Boron-silicon-containing arylacetylene polymer (PBSA) was synthesized through polycondensation reaction among diacetylenebenzene Grignard reagent, boron trichloride and dimethyldichlorosilane, and its structure was characterized by Infrared spectroscopy (FT-IR), Nuclear Magnetic Resonance spectroscopy (13C-NMR). The cure behavior of PBSA was investigated by using Differential Scanning Calorimetry (DSC), and the thermal and oxidative stability of cured PBSA were studied by Thermogravimetric Analysis (TGA) under nitrogen and air, respectively, the results indicated that ceramics derived from PBSA offer high thermal and oxidative stability.
Hybrid methacrylate–silica coatings derived from 3-(methacryloxypropyl)-trimethoxy silane were deposited on polycarbonate via hydrolysis–condensation reactions followed by UV curing (λ=253.7 nm). The formation of –Si–O–Si– (inorganic backbone) and polymethacrylate (organic) networks leading to the generation of hybrid structure was monitored by UV and Fourier transform infrared (FTIR) spectroscopies. UV and FTIR spectra showed complete polymerization of methacrylate groups during UV curing of the coatings. The silica network was initially formed through the hydrolysis–condensation reactions of alkoxy groups in the sol as evident from the appearance of FTIR peaks due to –Si–O–Si– vibrations. Further silanol (Si–OH) condensation reactions leading to the generation of more silica network were occurred simultaneously with methacrylate polymerization during UV photo curing of the coating.
The effects of Ag on Mn/SBA-15 catalysts have been investigated in the toluene catalytic oxidation. The reactivity of catalysts is related closely to the Ag/Mn molar ratio, and the sample with 1:3 of Ag/Mn molar ratio exhibits the highest reactivity for toluene oxidation, with a complete conversion at 260 °C. Based on the characterization results, it is found that Ag enters into MnO2 phase, and the Ag1.8Mn8O16 mixed phase forms. Meanwhile Ag leads to parts of MnO2 being transformed into Mn2O3. The Ag/Mn molar ratio has a strong influence on the molar ratio of the surface Mn4+ to Mn3+ and surface adsorbed oxygen (Oads) to lattice oxygen (Olatt) through the interaction between silver and MnOx. The coexistence of MnO2, Mn2O3, Ag1.8Mn8O16, and the strong interactions between Ag and Mn species exhibit a good synergetic interaction, which promotes the reducibility of catalysts and the formation of abundant active lattice oxygen, thus increasing the catalytic activity of toluene oxidation. And the formation of intermediate benzaldehyde should be closely link with the lattice oxygen of the Mn based catalyst.
This paper describes the FT-IR microspectroscopic imaging measurements of 5-μm diameter particles and demonstrates the associated optical non-linearities, due to chromatic aberration and diffraction. FT-IR microscopes with single-element detector use image masking in order to minimize the optical effect due to diffraction. Image masking cannot be used in the focal-plane array detector microscopes. The work presented here demonstrates that, through the application of multivariate curve resolution (MCR), the chemically significant information can be separated from the optical non-linearities. An improvement of the spatial resolution is achieved through the use of multivariate images of individual components, compared to univariate images at long wavelength.
The non-sulfided NiMoCe/Al2O3 catalyst was developed to produce green diesel from the hydroprocessing of Jatropha oil. The NiMoCe/Al2O3 catalysts were prepared by impregnation and characterized by N2-BET, SEM, XRD and TPD-Hads techniques. The straight chain alkanes ranging from C15 to C18 were the main components in product oil. The maximum yield of C15-C18 alkanes of 80%, selectivity of 90% and conversion of 89% were obtained at 370 °C, 3.5 MPa and 0.9 h−1. Influence of reaction temperature (280–400 °C) and reaction time (10–163 h) on the composition of product oil were discussed. The experimental results demonstrated that a suitable amount of metal Ce doping on the NiMo/Al2O3 catalyst presented stable catalytic performance and enhanced Jatropha oil conversion as well as C15-C18 fraction selectivity.
The first examples of thermally stable molecular dihydrogen adducts of nickel were synthesized from their dinitrogen adduct precursors, which are themselves among the first examples of Ni(II)-N2 complexes. The minimal activation of the bound N2 moieties suggests that these adducts are stabilized predominantly through σ-donation from the adduct to the electrophilic metal center. We further show that the bound H2 ligand can undergo heterolytic cleavage to deliver hydride to the nickel center. The H2 adducts are of particular interest in the context of hypotheses suggesting that Ni can serve as the site for H2 binding and heterolytic activation in [NiFe] hydrogenases.
The main objective of the present study is to gain further insight into the mechanism of toluene and methylcyclohexane photocatalytic oxidation on TiO2–ZrO2 thin-films, in order to understand the influence of the chemical nature of the pollutants on the deactivation process. Despite the significant differences in the physicochemical characteristics of these two molecules, the parallel study of their photocatalytic degradation can contribute to ascertain relevant aspects of the mineralization mechanism. This knowledge could be used for developing feasible solutions for this deactivation problem, which hinders a wider use of photocatalysis for air purification. The operando study of toluene photooxidation, a simultaneous analysis of surface and gas phase during reaction by using two FTIR spectrometers in tandem, allowed us to correlate the deactivation process with the formation of benzoic acid, strongly adsorbed on the surface as benzoate complexes. These species block the access of new organic molecules to the active sites and simultaneously hinder charge transfer from the photoactivated surface. As a consequence, the degradation rate of toluene considerably decreases after a few minutes of reaction. In contrast, intermediate surface complexes can be almost completely removed during the photocatalytic oxidation of methylcyclohexane. Therefore, it seems that the aromaticity of toluene plays a key role in the performance of photocatalysts during its degradation. The high stability of benzyl radicals favors the photocatalytic oxidation of this volatile organic compound (VOC) and the formation of recalcitrant oxygenated aromatic molecules which accumulate on the photoactive surface.
Raman spectra of argon matrix-isolated ozone and oxygen-18 enriched ozones were obtained using reduced power argon ion laser excitation. Photodecomposition of ozone was sufficiently moderated to obtain excellent Raman spectra, with the following 16O 3 assignments: v 1, 1104 cm -1, very strong; v 2, 701 cm -1, strong; v 3, 1038 cm -1, weak. Infrared spectra provided complementary data: v 1, 1105 cm -1, very weak; v 2, 704 cm -1, weak; v 3, 1040 cm -1, very strong. Potential constants were calculated using vibrational fundamentals for six isotopic ozone molecules. An ozone valence angle of 116.3 ± 4° was calculated from four isotopic v 3 assignments, in excellent agreement with the microwave value.
The monomer 4-benzyloxyphenylmethacrylate (4-BOPMA) was synthesized by reacting 4-benzyloxy phenol dissolved in methylethylketone
(MEK) with methacryloyl chloride in the presence of triethylamine. The homopolymer and various copolymers of 4-BOPMA with
butylmethacrylate (BMA) were synthesized by the free radical polymerization in MEK at 70 ± 1 °C in nitrogen atmosphere using
benzoylperoxide as initiator. The homopolymer and copolymers were characterized by various spectral techniques like IR, 1H-NMR, 13C-NMR spectroscopic techniques. The molecular weights of the polymers were determined by gel permeation chromatography. The
glass transition temperatures of polymers were determined by differential scanning calorimeter. The thermal stability of the
polymers was performed by thermo gravimetric analysis in inert atmosphere. The monomer reactivity ratios were determined using
the conventional linearization methods such as Fineman–Ross (r1 = 0.438, r2 = 0.2323), Kelen Tüdös (r1 = 0.4648, r2 = 0.2992) and extended Kelen Tüdös (r1 = 0.4489, r2 = 0.2616).
The dispersive properties of plasmonic metamaterials and the ability to tailor their complex transmission strongly suggest their use in versatile optical elements. Here we introduce the idea of such an application in diffractive elements and describe, as a proof-of-principle, two numerical implementations of computer-generated holograms at visible wavelengths that are based on fishnet metamaterials. These holograms consist of large arrays of metamaterial unit cells which have locally varying geometrical parameters into which the desired far-field optical response is encoded. We describe the entire design process for such holograms, discuss their efficiency and critically assess their limitations.
Fourier band analysis is applied to obtain the reorientational correlation functions from IR spectra of ordered nematic liquid crystals. Applying the equations derived in this work on vibrations not symmetric about the long molecular axis the rotational diffusion coefficient Drot of 4, n‐octyl 4′‐ethoxytolane molecules in nematic phase was determined and its temperature dependence was investigated. It is shown that Drot can also be obtained using the differences in the half‐widths of a band recorded with E∥n and E⊥n. This was done for both 4, n‐pentyl 4′‐methoxytolane and 4, n‐octyl 4′‐ethoxytolane. The molecular dynamics in the investigated aligned nematic phase is also discussed.
Time-resolved FT-IR spectroscopy was performed to monitor the behaviour of ferroelectric liquid crystals on a microsecond time scale. A bookshelf geometry was obtained by alignment with SiO obliquely evaporated layers in a CaF2 cell with 2 μm gap. Six kinds of FLC mixtures were examined, all of which were three-component systems consisting of chiral molecules of 5 wt% and two kinds of phenyl pyrimidine molecules of 47·5 wt% each. All IR spectra were dominated by vibrational modes from the phenyl pyrimidines. Typical vibrational modes from core and alkyl chain parts are selected in order to compare the movement of the alkyl chain as a function of the chiral components. A novel parameter α = (intensity of largest peak at 2925 cm/intensity of smallest peak at 2925 cm)/(intensity of largest peak at 1432 cm/intensity of smallest peak at 1432 cm) for evaluating the alkyl chain movement is introduced. It was found that the length of the rigid or flexible parts of the chiral molecules and the parameter α are correlated. Moreover, relations between the cone angle and α and between the rise time and α were found.
Two diketo-pyrrolo-pyrrole-based donor–acceptor copolymers, PCPDT–PDPP and PDTP–PDPP, were synthesized and applied as p-type component for bulk heterojunction solar cells. Using a facile molecular engineering of the main chain linking bridge, we have successfully tuned the band gap of the materials from low to medium level, which results in an improved balance between the device open circuit voltage and short circuit current. The power conversion efficiencies of the polymer/PC70BM combinations achieve 2.03% (PCPDT–PDPP) and 1.32% (PDTP–PDPP) without any interface engineering or post-treatment. A totally different composition-dependent photovoltaic behavior was also discovered for each of the two materials, although they share similar donor–acceptor (D–A) structure. Morphological and photophysical studies reveal a phase structure dominated, light harvesting subordinated mechanism, in which some nonkernel molecular level factors, such as the branch chain density and the molecular weight, are found to play important roles.
The decomposition of volatile organic compounds (VOCs)—six aromatic compounds of benzene derivatives and formic acid—was investigated using a plasma-driven catalysis (PDC) system at atmospheric pressure. In the PDC reactor, the decomposition efficiency of VOCs was mostly determined by the specific input energy (SIE) and insensitivity to the gas hourly space velocity from 11 000 to 55 000 h−1. Formic acid (HCOOH) was formed as a common intermediate from the decomposition of the tested aromatic compounds. Formic acid was also found to be an important intermediate for CO2 formation. Except for styrene, all the tested VOCs indicated zero-order kinetics, which confirm the dominant role of the catalytic reaction in the decomposition of VOCs using the PDC reactor. A simple kinetic model represents well the observed zero-order kinetics with respect to the SIE. Unlike conventional plasma reactors, no correlation between the ionization potential and the decomposition was found with the PDC reactor. Continuous operation tests indicated stable performance without deterioration of catalytic activity over 150 h.
Silk fabric was finished using acrylic acid (AA) as the finishing agent in the presence of sodium citrate and potassium per oxodisulphate catalysts separately or in selected combinations employing a pad-dry-cure technique. Treatment with 6% AA at 30°C and at pH 7 produced optimum effects; a batching time of 45–60 min at 30°C, followed by drying of the batched fabric at 95°C for 5 min and curing of the dried fabric at 140°C for 5 min produced most balanced improvements in the properties such as wrinkle recovery, extensibility, and moisture regain with retention of more than 80% of original strength. Sodium citrate catalyst allowed esterification of AA with proteineous constituent of silk and potassium per sulfate catalyst allowed radical polymerization of free AA or silk bound AA moieties; the said process ultimately led to some degree of crosslinking of the chain polymers of silk. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
To improve toluene removal efficiency and reduce byproducts, a TiO2/γ-Al2O3/nickel foam catalyst was combined in and after the non-thermal plasma (NTP), leading to a plasma-driven catalysis (PDC) and plasma-assisted catalysis (PAC) process, respectively. The addition of catalysis could significantly enhance the toluene destruction with an increased CO2 selectivity and carbon balance while the byproducts, such as O3 and organic compounds, were dramatically reduced. The PAC exhibited the highest efficiency in toluene destruction due to the formation of more atomic oxygen and hydroxyl radicals from O3 catalytic decomposition. The pathways of toluene destruction by NTP and plasma-catalysis were proposed according to the identified intermediates.Graphical abstractThe pathways of toluene destruction by energetic electrons are greatly different to that by O/OH, which accounts for much less byproducts in the plasma-catalysis process.View high quality image (112K)Research highlights▶ The catalyst could significantly enhance the toluene destruction and reduce byproducts. ▶ The PAC process exhibited the highest efficiency in both toluene and O3 destruction. ▶ More reactive species from O3 catalytic decomposition is responsible for the increased activity. ▶ The pathways of toluene destruction in plasma-catalysis are greatly different to that in the NTP alone.
In situ FTIR spectroscopy was used to identify the adsorbed species and the intermediates during methanol dehydrogenation over Cu/SiO2 catalyst, and a schematic reaction network was proposed. Methoxy species on copper, which were derived from adsorbed methanol, dehydrogenated into formaldehyde. Then several competitive pathways took place. The adsorbed formaldehyde could desorb to the gas phase, or react with another adsorbed methoxy group to form methyl formate, and/or undergo further dehydrogenation to CO and H2. Carbon monoxide formed from the decomposition first adsorbed on high-index planes of copper, and then on low-index planes as the reaction progressed. With the increase of temperature, the concentration of formaldehyde and CO in gas phase increased, and that of methyl formate decreased.
Silver colloids have been prepared by reducing AgNO3 in aqueous solution and embeded in alumina following a sol–gel procedure in the presence of Pluronic 84 ((EO)19(PO)39(EO)19), as surfactant. Plasma-catalytic experiments aimed at the mineralization of toluene showed that the selectivity to CO2 was significantly increased in the presence of Ag catalysts compared with results obtained using the plasma alone. In-situ studies of the ozone interaction with catalysts provide an insight into the nature of the active sites of supported silver colloids for mineralization reactions. It is noticeable that when ozone is chemisorbed on embedded Ag colloidal catalysts no change in the silver oxidation state or size is found. The population of the chemisorbed species is higher at lower temperatures, where the non-selective decomposition of ozone is smaller. The catalysts exhibit high stability, preserving the structural and textural properties after the catalytic tests, that is indeed very important in the presence of ozone.Graphical abstractHighlights► Silver colloids embedded in alumina following a sol–gel procedure in the presence of Pluronic 84 are stable catalysts in the presence of ozone. ► Plasma-catalytic experiments in the total oxidation of toluene showed a significantly increased selectivity to CO2 in the presence of Ag embedded colloids. ► In situ studies of the ozone interaction with catalysts provide an insight into the nature of the active sites of supported silver colloids for total oxidation reactions.
Natural fibres are envisaged today as potential candidates for replacing glass fibres in composite materials. Although natural fibres have a number of advantages over glass fibres, the strong polar character of their surface is a limiting factor as, compatibility with strongly apolar thermoplastic matrices is very low. Such problems of incompatibility may be overcome with fibre pre-treatments, which can enhance compatibility although having a negative impact on the economics of using such materials. In this study two fibre pre-treatment methods, acetylation and stearic acid treatments, have been applied on flax fibres. The effect of these two pre-treatments has been examined by use of XPS, ToF-SIMS and FTIR spectroscopic methods. It was found that the fibre surface before treatment is very different to what may have been expected for cellulose materials. There is an appreciable coverage of the flax fibre surface with hydrocarbon compounds, possibly waxy substances, but no aromatic compounds were detected. All three spectroscopic methods revealed that the fibre surface chemistry has been altered after the treatments, and especially for acetylation it was found that ester bonds are present on the fibre surface after treatment. For the stearic acid treatment the situation still remains less conclusive. Finally, ToF-SIMS experiments revealed that the coverage of the fibre surface with acetyl groups and stearic acid is highly heterogeneous.
The introduction of ferroelectric and catalytically active materials into the discharge zone of NTP reactors is a promising
way to improve their performance for the removal of hazardous substances, especially those appearing in low concentrations.
In this study, several coaxial barrier-discharge plasma reactors varying in size and barrier material (glass, Al2 O3, and TiO2) were used. The oxidation of methyl tert-butyl ether (MTBE), toluene and acetone was studied in a gas-phase plasma and in various packed-bed reactors (filled with
ferroelectric and catalytically active materials). In the ferroelectric packed-bed reactors, better energy efficiency and
CO2 selectivity were found for the oxidation of the model substances. Studies on the oxidation of a toluene/acetone mixture in
air showed an enhanced oxidation of the less reactive acetone related to toluene in the ferroelectric packed-bed reactors.
It can be concluded that the change of the electrical discharge behaviour was caused by a larger number of non-selective and
highly reactive plasma species formed within the ferroelectric bed. When combining ferroelectric (BaTiO3) and catalytically active materials (LaCoO3), only a layered implementation led to synergistic effects utilising both highly energetic species formed in the ferroelectric
packed-bed and the potential for total oxidation provided by the catalytically active material in the second part of the packed
bed.
Vibrational spectral analysis and quantum chemical computations based on density functional theory (DFT) have been performed on the organic crystal l-prolinium picrate (LPP). The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of LPP have been investigated using B3LYP method. The calculated molecular geometry has been compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA 4 program. The various intramolecular interactions confirming the biological activity of the compound have been exposed by natural bond orbital analysis. The distribution of Mulliken atomic charges and bending of natural hybrid orbitals associated with hydrogen bonding also reflects the presence of intramolecular hydrogen bonding thereby enhancing bioactivity. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicates electron transport in the molecule and thereby bioactivity. Vibrational analysis reveals the presence of strong O-H⋯O and N-H⋯O interaction between l-prolinium and picrate ions providing evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity.
A rapid, simple, and environmentally friendly Fourier transform infrared (FTIR) spectroscopic method has been developed to directly determine 2-thiobarbituric acid reactive substances (TBARS) in palm olein. Two multivariate methods, partial least squares (PLS) and principal component regression (PCR), were used to build the calibration models that correlate the chemical 2-TBARS values to the selected spectral regions of FTIR data. The calibration models obtained were cross-validated with ‘leave-one-out’ method before applying to predict the TBARS values in palm olein. However, the calibration models obtained from the PLS method gave lower standard errors of prediction (SEP) compared to PCR. With the spectrometer calibrated, the predicted 2-TBARS results could be obtained within 5 min per sample, a major improvement over the conventional wet chemical method.
Methods for hybridization of silent discharge plasma and catalysts in different forms are presented, and their synergy in benzene decomposition is discussed. TiO2 deposition on the inside wall of the coaxial type of the silent discharge plasma reactor promotes benzene decomposition in air and increases CO2 yield. TiO2–silica gel granules housed inside of the punched internal electrodes also facilitate the oxidative decomposition of benzene. Comparison of the TiO2 surface before and after the reactions by FTIR suggests that the positive effect of TiO2 can be ascribed to the active oxygen species generated on its surface. Replacement of TiO2–silica gel by MnO2 also promotes the oxidative decomposition of benzene in silent discharge plasma. Ozone, which is generated from gaseous oxygen, is decomposed by MnO2, but not by TiO2. Catalytic effects of TiO2 and MnO2 can be ascribed to formation of active oxygen species on their surfaces and that of the triplet oxygen atom from ozone on the MnO2 surface. It has been shown that both of TiO2 and MnO2 can sustain their catalytic activities in silent discharge plasma.
In this work, Ag-doping TiO(2) nanotubes were prepared and employed as the photocatalyst for the degradation of toluene. The TiO(2) nanotube powder was produced by the rapid-breakdown potentiostatic anodization of Ti foil in chloride-containing electrolytes, and then doped with Ag through an incipient wetness impregnation method. The samples were characterized by scanning electron microscope, high-resolution transmission electron microscopy, X-ray diffraction, surface photovoltage measurements, X-ray photoelectron spectroscopy and N(2) adsorption. The nanotubular TiO(2) photocatalysts showed an outer diameter of approximately 40nm, fine mesoporous structure and high specific surface area. The photocatalytic activity of Ag-doping TiO(2) nanotube powder was evaluated through photooxidation of gaseous toluene. The results indicated that the degradation efficiency of toluene could get 98% after 4h reaction using the Ag-doping TiO(2) nanotubes as the photocatalyst under UV light illumination, which was higher than that of the pure TiO(2) nanotubes, Ag-doping P25 or P25. Benzaldehyde species could be observed during the photocatalytic oxidation monitored by in situ FTIR, and the formed benzaldehyde intermediate during reaction would be partially oxidized into CO(2) and H(2)O.
Titanium-tungsten nanocrystals (NCs) were fabricated by a self-assembly rapid thermal annealing (RTA) process. Well isolated Ti(0.46)W(0.54) NCs were embedded in the gate dielectric stack of SiO(2)/Al(2)O(3). A metal-oxide-semiconductor (MOS) capacitor was fabricated to investigate its application in a non-volatile memory (NVM) device. It demonstrated a large memory window of 6.2 V in terms of flat-band voltage (V(FB)) shift under a dual-directional sweeping gate voltage of - 10 to 10 V. A 1.1 V V(FB) shift under a low dual-directional sweeping gate voltage of - 4 to 4 V was also observed. The retention characteristic of this MOS capacitor was demonstrated by a 0.5 V memory window after 10(4) s of elapsed time at room temperature. The endurance characteristic was demonstrated by a program/erase cycling test.