Analysis Of Volatile Products Research Articles

Natural resin-derived urushiol-based phosphorylation derivative towards flame-retardant and mechanically strong epoxy resin

Biobased flame retardants have attracted great attention owing to their environmental friendliness and easy availability. Urushiol, extracted from natural resin-raw lacquer, has been capped with diphenylphosphoryl chloride to afford a biobased flame retardant, namely urushiol-based phosphonate (U-DC). As an additive this material is effective in reducing flammability while maintaining good mechanical strength for epoxy resins (EP). Impressively, an EP/9 %U-DC blend exhibits a UL-94 V-0 rating, and an LOI of 37.1 % for combustion. Further, compared to that for EP, the peak heat release rate (pHRR) and total heat release (THR) for the EP/9 %U-DC blend was lower by 40.5 % and 26.6 %. Through analysis of volatile products formed and char residue produced during polymer degradation, a mode of flame retardant action for U-DC has been proposed. Further, EP/U-DC blends display better mechanical properties than those of unmodified EP. Tensile strength of EP containing 7 wt% U-DC (81.6 MPa) is greater than that for unmodified EP (64.4 MPa). This may be ascribed to the presence of abundant rigid benzene units in U-DC and chain entanglement between the long side chain of U-DC and the epoxy macromolecular chain. These observations provide a basis for the utilization of new urushiol derivatives in the production of high-performance EP.

Hydrogen-Free Deoxygenation of Oleic Acid and Industrial Vegetable Oil Waste on CuNiAl Catalysts for Biofuel Production

The pyrolysis of vegetable oil waste is an alternative way to convert biomass into high-quality second-generation biofuels, with social, economic and environmental sustainability. The present work deals with the pyrolysis of oleic acid as a model compound and an industrial vegetable oil residue on CuNiAl mixed oxide catalysts, derived from layered double hydroxides. Reactions of the oils pre-adsorbed on the catalysts (catalyst:oil mass ratio of 5:1) were performed at 550 °C on a micro-pyrolysis system and the analyses of volatile products were carried out online using GC/MS. Copper addition to NiAl catalysts increased the cracking of oleic acid. Increasing copper content also decreased the formation of aromatics and coke precursors, as well as oxygenated compounds. The CuNiAl catalyst with a Cu/Ni ratio of 0.4 showed strong catalytic activity in the conversion of an industrial vegetable oil residue with a high volume of free fatty acids produced. Compared to the non-catalytic reaction, the catalyst reduced the content of oxygenates and increased the content of hydrocarbons, particularly in the gasoline range (C5–C9). The CuNiAl oxide catalyst was able to convert vegetable oil residues into hydrocarbons in the range of gasoline, kerosene and diesel, and also linear alkylbenzenes as chemical precursors for surfactant production.

Co-pyrolysis of municipal and horticultural wastes for enhanced biochar and bio-oil production: A response surface methodology approach

Pyrolytic biochar is a promising approach to the withdrawal of CO2 and reduction of Green House Gases. One of the effective techniques to improve the properties of biochar with desired characteristics is co-pyrolysis of types of biomass. Among the types of biochar, biochar from nitrogen-rich biomass pyrolysis has various applications, including soil amendment and removal of organic pollutants. The aim of this study is co-pyrolysis nutrient-rich municipal (household) and horticultural wastes for N-doped biochar production and provide optimal conditions for the production of pyrolytic products. A series of experiments were designed with municipal and horticultural wastes at different mass ratios in a fast catalytic reactor at 550 °C with varying catalyst amounts (0–15 %) and waste blend ratios (0–100 wt%) were designed using the response surface methodology. The yields of bio-oil, biochar, and biogas were quantitatively and qualitatively assessed. Statistical analysis showed that that the horticultural-to-household wastes ratio has the most critical effect on the biochar yield. The optimum N-doped biochar yield (26 wt%) was achieved at the household-to-horticultural wastes ratio of 1.5 without using the catalyst. Also, the result showed that adding municipal waste increased bio-oil yield significantly from 18 % to 58 %. Moreover, increasing the catalyst amount raised gas yield to 37 %, and horticultural waste favored biochar formation (53 %). The optimized product showed carbon enrichment and oxygenated compound reduction the result is bio-oil production with a higher heating value. Gas chromatography-mass spectrometry (GC–MS) analysis of volatile products indicated that the co-pyrolytic oil was rich in N-containing compounds (Pyrrole, Pyridine, and Indole)which is widely used in pharmaceutical and polymer industries. Synergistic interactions between municipal and horticultural wastes significantly reduced the amount of carboxylic acids, alcohols, ketones, and esters, whereas phenols formation as valuable chemicals were increased. Therefore, this study shows that co-pyrolysis is a suitable approach for household and horticultural waste management that can increase the production of N-doped biochar and also be a sustainable source for the extraction of nitrogen-containing biochemical products.

Thermal properties and fire behavior of a flexible poly(vinyl chloride) modified with complex of 3-aminotriazole with zinc phosphate

The complex of zinc phosphate and 3-amine-1,2,4-triazole (ZN3AT) was synthesized by a one-pot reaction and used as an intumescent flame retardant (IFR) for flexible poly(vinyl chloride) (PVC). The thermal properties and fire behaviour of flexible PVC with 20 wt% of ZN3AT were investigated and compared with unmodified PVC and PVC with commercial IFR. The thermal stability and burning behaviour were evaluated by thermogravimetric analysis (TGA) as well as cone calorimetry and horizontal burning tests. Furthermore, the analysis of volatile products evolved during the thermal decomposition and burning was performed using TGA and steady state tube furnace, both coupled with FT-IR. PVC containing developed flame retardant exhibits the lowest total heat release and smoke emission of all investigated samples. Materials analysis supplemented with analysis of their mechanical and thermomechanical properties shows that despite the high concentration of the IFR its incorporation did not strongly influence the properties of final products in comparison to pure PVC.

Moisture Resistance, Thermal Stability and Fire Behavior of Unsaturated Polyester Resin Modified with L-histidinium Dihydrogen Phosphate-Phosphoric Acid.

In this paper, the fire behavior of unsaturated polyester resin (UP) modified with L-histidinium dihydrogen phosphate-phosphoric acid (LHP), being a novel intumescent fire retardant (IFR), was investigated. Thermal and thermomechanical properties of the UP with different amounts of LHP (from 10 to 30 wt. %) were determined by thermogravimetric analysis (TG) as well as dynamic mechanical thermal analysis (DMTA). Reaction to small flames was studied by horizontal burning (HB) test, while fire behavior and smoke emission were investigated with the cone calorimeter (CC) and smoke density chamber. Further, the analysis of volatile products was conducted (TGA/FT-IR). It was observed that the addition of LHP resulted in the formation of carbonaceous char inhibiting the thermal decomposition, burning rate and smoke emission. The most promising results were obtained for the UP containing 30 wt. % of LHP, for which the highest reduction in maximum values of heat release rate (200 kW/m2) and total smoke release (3535 m2/m2) compared to unmodified polymer (792 kW/m2 and 6895 m2/m2) were recorded. However, some important disadvantage with respect to water resistance was observed.

Py-FTIR-GC/MS Analysis of Volatile Products of Automobile Shredder Residue Pyrolysis.

Automobile shredder residue (ASR) pyrolysis produces solid, liquid, and gaseous products, particularly pyrolysis oil and gas, which could be used as renewable alternative energy resources. Due to the primary pyrolysis reaction not being complete, the yield of gaseous product is low. The pyrolysis tar comprises chemically unstable volatiles before condensing into liquid. Understanding the characteristics of volatile products will aid the design and improvement of subsequent processes. In order to accurately analyze the chemical characteristics and yields of volatile products of ASR primary pyrolysis, TG–FTIR–GC/MS analysis technology was used. According to the analysis results of the Gram–Schmidt profiles, the 3D stack plots, and GC/MS chromatograms of MixASR, ASR, and its main components, the major pyrolytic products of ASR included alkanes, olefins, and alcohols, and both had dense and indistinguishable weak peaks in the wavenumber range of 1900–1400 cm−1. Many of these products have unstable or weaker chemical bonds, such as =CH–, =CH2, –C=C–, and –C=CH2. Hence, more syngas with higher heating values can be obtained with further catalytic pyrolysis gasification, steam gasification, or higher temperature pyrolysis.

Synergistic effect between histidine phosphate complex and hazelnut shell for flammability reduction of low-smoke emission epoxy resin

A novel intumescent fire retardant (FR) system based on ground hazelnut shell (HS) and L-histidinium dihydrogen phosphate-phosphoric acid (LHP) was introduced into the epoxy resin (EP) in order to verify their effectiveness as fire retardant. The burning behaviour and smoke emission were assessed with cone calorimeter (CC) and UL-94 tests. Furthermore, the analysis of volatile products evolved during both the thermal decomposition and burning was conducted with the use of thermogravimetric analysis (TGA/FT-IR) and steady-state tube furnace (Purser/FT-IR), both combined with FT-IR with the use of a transfer line. It was found that the system containing 5 wt% of HS and 15 wt% of LHP lead to in the formation of a swollen char with numerous closed cells, which reduced the burning process as well as smoke emission. The obtained results confirm the occurrence of a synergistic effect between the components.

Thermal properties and fire behavior of polyethylene with a mixture of copper phosphate and melamine phosphate as a novel flame retardant

In this study mixture of copper phosphate and melamine phosphate (CUMP) was introduced into high-density polyethylene (HDPE) and examined. The thermal effects of the developed materials were analysed using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) as well as thermogravimetric analysis (TGA). The reaction to fire of the HDPE with a developed flame retardant (FR) was determined by cone calorimetry (CC). The microstructure of the samples and char residues after the CC tests were assessed with a scaning electron microscope (SEM). Moreover, the analysis of volatile products evolved during the thermal degradation and burning was performed using TGA (TGA/FT-IR), as well as steady state tube furnace (Purser/FT-IR), both coupled with FT-IR. It was found that the presence of copper catalyzes the degradation process, which may have a beneficial impact on char formation. Degradation in lower temperature range allows shorter hydrocarbon chains to undergo the cyclization process forming more complex aromatic structures, which are significantly more thermally stable and contribute to the formation of the char layer. PE/CUMP formed more char compared to the PE as well as PE with comercial FR. However, some disadvantages regarding smoke emission, connected with long smoldering time, were observed.

Utilisation of methylcellulose as a shaping agent in the fabrication of Ba0.95Ca0.05Ce0.9Y0.1O3 proton-conducting ceramic membranes via the gelcasting method

The gelcasting method was used to form gastight Ba0.95Ca0.05Ce0.9Y0.1O3 samples proposed for use as proton-conducting electrolytes in solid oxide fuel cells. Methylcellulose was used as an environmentally friendly shaping agent for Ba0.95Ca0.05Ce0.9Y0.1O3 powder in an ethanol solution. Samples of Ba0.95Ca0.05Ce0.9Y0.1O3 were also prepared from the same powder via traditional isostatic pressing, as a reference for cast samples, and sintered in the same conditions. Comparative studies of the physicochemical properties of Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes, formed by means of these two methods and then sintered at 1550 °C for 2.5 h, were presented and discussed. Using the X-ray diffraction method, only the pure orthorhombic phase of BaCe0.9Y0.1O3 was detected in the Ba0.95Ca0.05Ce0.9Y0.1O3 powder, as well as in the Ba0.95Ca0.05Ce0.9Y0.1O3 sintered pellets formed via both gelcasting (A) and isostatic pressing (B). Thermal effects occurring during heating of methylcellulose, as well as ceramic Ba0.95Ca0.05Ce0.9Y0.1O3 powder, dried cast samples obtained from the prepared slurry, and sintered Ba0.95Ca0.05Ce0.9Y0.1O3 samples, were examined by differential scanning calorimetry, differential thermal analysis, thermogravimetric analysis, and evolved gas analysis of volatile products using a quadrupole mass spectrometer. The measurements were performed within the temperature range of 20–1200 °C in air. Based on dilatometric tests, it was found that the Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples exhibited slightly higher degree of sinterability than the 5CBCY samples obtained by isostatic pressing. In comparison with pressed pellets, higher values of total electrical conductivity in air or in a gas mixture of 5% H2 in Ar were also attained for Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples. The Ba0.95Ca0.05Ce0.9Y0.1O3 samples were used to construct oxygen–hydrogen electrolytes for solid oxide fuel cells. The results of the electrochemical performance of solid oxide fuel cells with Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes were comparable to the data in the literature on BaCe0.9Y0.1O3 electrolytes. An electrochemical study of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ|Ba0.95Ca0.05Ce0.9Y0.1O3 interface was also performed. Ba0.5Sr0.5Co0.8Fe0.2O3−δ appears to be a suitable cathode material for a Ba0.95Ca0.05Ce0.9Y0.1O3 electrolyte.

Effect of infrared laser radiation on gas-phase pyrolysis of ethane

Pyrolysis of hydrocarbons is widely used for the production of light olefins. The pyrolytic processes are energy-consuming, proceeding at high wall reactor temperature and producing large amounts of undesired carbonaceous side-products. There is a demand for the search of lower temperature regimes together with the reduction of side products at high conversion efficiencies. The objective of our research is to decrease the temperature of walls of the pyrolytic reactor for the ethane thermal decomposition by CO2-laser radiation. Gas-phase laser induced pyrolysis of ethane was studied in a continuous flow tubular reactor. Introduction of infrared laser radiation into the pyrolysis reactor results in significant reduction of the reaction temperature threshold and noticeable increase of the ethane conversion at temperatures 870–970 K. At low-temperature range, 760–920 K, significant increase of ethane conversion was observed in the presence of ethylene comprising 5–10 % vol. of the initial gas mixture. Similar shift of temperature threshold was also observed with the increase of radiation power density. Analysis of volatile products demonstrated minor differences in the product content for both conventional and laser-induced pyrolysis, thus confirming the laser radiation function as an additional energy source without significant interference in the gas phase reactions. From practical point of view the laser induced pyrolysis opens the possibility to save energy on the account of reduced temperature. The low-temperature pyrolysis could additionally be promoted by the introduction of unsaturated hydrocarbons.

Impedance Spectroscopy and Differential Electrochemical Mass Spectrometry As Tools for Characterization of Mediated Oxidation of Organic Pollutants

Persistent Organic Pollutants (POP) are hazardous environmental contaminants of mainly synthetic origin, highly toxic and chemically inert. They accumulate in the environment and in living organisms. Most POPs do not ignite themselves and they cannot be combusted. Therefore it is very important to find an alternative processes of POP neutralization. Mediated Electrochemical Oxidation has been proven to be an efficient approach, in which those dangerous substances are electrochemically combusted under ambient conditions. Mediated electrochemical oxidation is an indirect electrolysis, where pollutants are oxidized through the mediation of some electrochemically generated redox reagents, which act as an intermediary for electrons shuttling between the electrode and the target molecule. This technique enables the possibility to oxidize an (electro)inactive compounds.1 Recently, we have derived the exact analytical solution for impedance of catalytic processes involving redox mediators. The results obtained for general case in the rigorous treatment provide a powerful research tool that can be used in studies of many important catalytic processes.2 Unusual impedance characteristics have been found for systems having unequal diffusivities of the oxidized and reduced forms of the redox mediator. Depending on the ratio of diffusion coefficients the spectra are either markedly deformed at low frequency range or an inductive loop appears at the complex plane. It is impossible to fit these spectra in the whole frequency range, neither with the Gerischer impedance nor with any other known transfer function.2 We show that the key parameters of the studied systems, such as both heterogeneous and homogeneous rate constants, which are limiting factors for the electrochemical combustion efficiency, can be readily obtained even from a single impedance spectrum.2 In this research, silver(II) compounds were used as redox mediators for electrochemical combustion of organic molecules.3 As reported by us previously, the redox potential of the system Ag(II)/Ag(I) can reach up to 2.9V in sulfuric acid media.4 Moreover the average lifetime of the produced radical oxidant was estimated to be in order of seconds.5 Initially, investigations were carried out for a model organic molecule - acetic acid, which is known to be difficult to oxidize, and next for 1,2-dichlorobenzene an organic compound from POP group. The catalytic activity of Ag(II) was characterized mainly by using electrochemical methods with a particular emphasis placed on Electrochemical Impedance Spectroscopy (EIS). We have also performed analysis of volatile products by using mass spectrometry coupled with electrochemical measurements DEMS (Differential Electrochemical Mass Spectroscopy). This technique allows to detect in situ volatile electrooxidation products and/or intermediates. The latter were monitored for catalytic electrooxidation of acetic acid and 1,2-dichlorobenzene in function of electrode potential, for both compounds a large amount of CO2 was detected. 1. M. Panizza and G. Cerisola, Chemical Reviews, 2009, 109, 6541-6569. 2. R. Jurczakowski and P. Polczynski, J Phys Chem C, 2014, 118, 7980-7988. 3. M. Fleischmann and D. Pletcher, Tetrahedron Letters, 1968, 9, 6255-6258. 4. P. Polczynski, R. Jurczakowski and W. Grochala, Chem Commun, 2013, 49, 7480-7482. 5. P. Polczynski, R. Jurczakowski and W. Grochala, J Phys Chem C, 2013, 117, 20689-20696.

Brown coal gasification in combustion in supercritical water

The yield and composition of conversion products are investigated in a layout that provides countersupply of reagents (brown coal, supercritical water (SCW), and O2) into a vertical tubular reactor and drain of reactants into replaceable collectors under isobaric conditions (30 MPa). The coal (gross formula CH0.96N0.01S0.002O0.31) incorporated into coal-water slurry (CWS) stabilized by starch addition (1 wt.%), was supplied through the top end of the reactor, while SCW and SCW/O2 fluids were supplied through the bottom end. Based on the results of elemental analysis of liquid products and solid residue of conversion, and mass spectrometric analysis of volatile products, we obtained gross reactions of brown coal conversion in SCW and SCW/O2 fluids. It was found that addition of O2 to SCW leads to autothermal conversion conditions and an increase in the contribution from heterogeneous reactions between carbon and water, which provides additional yield of H2 and CH4.

In-situ analysis of volatile products from lignite pyrolysis with pyrolysis-vacuum ultraviolet photoionization and electron impact mass spectrometry

Pyrolytic species of two kinds of lignites (samples A and B) are investigated in-situ with pyrolysis-vacuum ultraviolet photoionization/electron impact mass spectrometry (PVUVPI/EIMS). Mass spectra of pyrolytic fragments are measured during temperature-programmed pyrolysis process of two lignite samples and the intensity profiles of the pyrolytic species are estimated in different temperatures. Experimental results show that H2, H2O, CO, and CO2 are dominant inorganic gaseous products and their characteristic temperatures are in accord with the temperatures of related chemical bonds cleavage. Mononuclear aromatics are dominant organic pyrolysis products, and many olefin species are also identified. The differences between samples A and B on macromolecular structures make the distribution of pyrolytic products different. In addition, the peak of H2S and CH3SH are both clearly observed in mass spectra of sample B, which could come from thioether bonds decomposition. This work also illustrates that the PVUVPI/EIMS performs very well in in-situ analysis pyrolytic products.

Comparison of thermal behavior of natural and hot-washed sisal fibers based on their main components: Cellulose, xylan and lignin. TG-FTIR analysis of volatile products

Abstract This paper presents in a comprehensive way the thermal behavior of natural and hot-washed sisal fibers, based on the fundamental components of lignocellulosic materials: cellulose, xylan and lignin. The research highlights the influence exerted on the thermal stability of sisal fibers by other constituents such as non-cellulosic polysaccharides (NCP) and mineral matter. Thermal changes were investigated by thermal X-ray diffraction (TXRD), analyzing the crystallinity index (%Ic) of cellulosic samples, and by simultaneous thermogravimetric and differential thermal analysis coupled with Fourier-transformed infrared spectrometry (TG/DTA-FTIR), which allowed to examine the evolution of the main volatile compounds evolved during the degradation under inert and oxidizing atmospheres. The work demonstrates the potential of this technique to elucidate different steps during the thermal decomposition of sisal, providing extensible results to other lignocellulosic fibers, through the analysis of the evolution of CO 2 , CO, H 2 O, CH 4 , acetic acid, formic acid, methanol, formaldehyde and 2-butanone, and comparing it with the volatile products from pyrolysis of the biomass components. The hydroxyacetaldehyde detected during pyrolysis of sisal is indicative of an alternative route to that of levoglucosan, generated during cellulose pyrolysis. Hot-washing at 75 °C mostly extracts non-cellulosic components of low decomposition temperature, and reduces the range of temperature in which sisal decomposition occurs, causing a retard in the pyrolysis stage and increasing Tb NCP and Tb CEL , temperatures at the maximum mass loss rate of non-cellulosic polysaccharides and cellulose decompositions, respectively. However, enriching sisal fibers in cellulose produces a decrease of Tb CEL under an oxidizing atmosphere, and furthermore, a delay of the combustion process, displacing Tb COM to higher temperatures. The results and findings of the paper would help further understanding of thermal processes where Agave fibers are involved, as the decomposition of their composites.

Real-time quantitative analysis of volatile products generated during solid-state polypropylene thermal oxidation

Analysis of volatile organic compounds (VOCs) during PP thermal oxidation under three oxygen partial pressures (0%, 21% and 100% of atmospheric pressure) at 140 °C was performed by proton transfer reaction coupled with Fourier transform ion cyclotron resonance mass spectrometry. Six main VOCs were identified: acetone, acetic acid, 2,4-pentanedione, acetaldehyde, formaldehyde and methyl acrolein. Their formation was shown to obey two main reaction pathways, both involving methyne units as driving oxidation sites: (i) the widely accepted chain scission mechanism of tertiary alkoxy radicals, which generates primary radicals undergoing secondary reactions leading to the oxidation of methylene units; (ii) the chain scission mechanism occurring on tertiary alkyl radical, which is proposed here as a realistic path leading to methyl acrolein. The relative proportions of the six main VOCs depend on the oxygen partial pressure, which mostly impacts the oxidation of methylene units rather than the competition between the two previous paths.

Online Analysis of Volatile Products from Bituminous Coal Pyrolysis with Synchrotron Vacuum Ultraviolet Photoionization Mass Spectrometry

Volatile species from pyrolysis of two kinds of bituminous coal, Huainan (HN) and Yima (YM), were investigated online with tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Mass spectra of products at different photon energies and temperatures were measured during the pyrolysis process. Some isomeric products can be characterized by the SVUV-PIMS based on their different ionization energies. Aromatic compounds are dominant pyrolysis products of these coal samples, while a number of aliphatic products were also observed. In comparison of these two coals, the HN coal probably has more condensed aromatic structures than YM coal. The different structures of the macromolecular network between HN and YM coals probably lead to different pyrolytic products at the same temperature. This work demonstrates the good performance of SVUV-PIMS in online analysis of complex coal pyrolysis.

Conversion of brown coal in sub- and supercritical water at cyclic pressurization and depressurization

The conversion of brown coal in sub- and supercritical water at 310–460°C and pressures up to 30 MPa in the cyclic pressurization and depressurization modes is studied. The temperature dependences of coal organic matter (COM) conversion and the yield of volatile and condensed products are obtained. The temperature dependence of the yield of condensed substances has a maximum at 370°C. The fraction of high-molecular substances in condensed products is increased with increasing temperature. The cumulative conversion of COM into volatile and condensed products upon heating to 460°C was 31.4 and 8.6%, respectively. According to the data of mass spectrometry analysis of volatile products and the elemental analysis of the initial coal, carbonaceous residue after the conversion, and condensed products, 82.3% of oxygen and 74.7% of sulfur, are removed from COM. CO2 and H2S are the main products of the conversion of oxygen- and sulfur-containing groups.

Pyrolysis study of poly(trimethylene terephthalate) and its phosphorus-containing copolyesters

This paper deals with the thermal decomposition behavior of PTT and its two different phosphorus-containing copolyesters, one containing 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP) with phosphorus in the pendent group, the other containing bis-4-carboxyphenyl phenyl phosphine oxide (BCPPO) with phosphorus in the backbone. TGA-FTIR and Pyrolysis-GC/MS were used to investigate the corresponding volatile products under nitrogen atmosphere. Both PTT and its phosphorus-containing copolyesters showed one decomposition stage between 330 and 446 °C. The introduction of phosphorus decreased the onset decomposition temperature due to the comparative weak P–C bond. No obvious absorption peak of P–C bond is detected with FTIR in volatile products for its low content and weak absorption. The analysis of volatile products of TGA and Pyrolysis-GC/MS revealed that they underwent different way of thermal decomposition for the different decomposition conditions. Possible thermal decomposition schemes are proposed and mass spectra of some decomposition products are also listed.

UV laser photodeposition of nanomagnetic soot from gaseous benzene and acetonitrile–benzene mixture

Megawatt KrF laser gas-phase photolysis of benzene and acetonitrile–benzene mixture was studied by using mass spectroscopy–gas-chromatography and Fourier transform infrared spectroscopy for analyses of volatile products, and by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, electron microscopy and magnetization measurements for analyses of solid products deposited from the gas-phase. The results are consistent with carbonization of benzene and decomposition of non-absorbing acetonitrile in carbonizing benzene through collisions with excited benzene and/or its fragments. The solid products from benzene and acetonitrile–benzene mixture have large surface area and are characterized as nanomagnetic amorphous carbonaceous soot containing unsaturated C centers prone to oxidation. The nanosoot from acetonitrile–benzene mixture incorporates CN groups, confirms reactions of benzene fragments with CN radical and has a potential for modification by reactions at the CN bonds.

Reactions of ozone with human skin lipids: Sources of carbonyls, dicarbonyls, and hydroxycarbonyls in indoor air

This study has used proton transfer reaction-mass spectrometry (PTR-MS) for direct air analyses of volatile products resulting from the reactions of ozone with human skin lipids. An initial series of small-scale in vitro and in vivo experiments were followed by experiments conducted with human subjects in a simulated office. The latter were conducted using realistic ozone mixing ratios (approximately 15 ppb with occupants present). Detected products included mono- and bifunctional compounds that contain carbonyl, carboxyl, or alpha-hydroxy ketone groups. Among these, three previously unreported dicarbonyls have been identified, and two previously unreported alpha-hydroxy ketones have been tentatively identified. The compounds detected in this study (excepting acetone) have been overlooked in surveys of indoor pollutants, reflecting the limitations of the analytical methods routinely used to monitor indoor air. The results are fully consistent with the Criegee mechanism for ozone reacting with squalene, the single most abundant unsaturated constituent of skin lipids, and several unsaturated fatty acid moieties in their free or esterified forms. Quantitative product analysis confirms that squalene is the major scavenger of ozone at the interface between room air and the human envelope. Reactions between ozone and human skin lipids reduce the mixing ratio of ozone in indoor air, but concomitantly increase the mixing ratios of volatile products and, presumably, skin surface concentrations of less volatile products. Some of the volatile products, especially the dicarbonyls, may be respiratory irritants. Some of the less volatile products may be skin irritants.