Pyrolysis-gas Chromatography Method Research Articles

Polycyclic aromatic hydrocarbons in biochar originated from pyrolysis of aseptic packages (Tetra Pak®)

Determination of the total yield of polycyclic aromatic hydrocarbons (PAHs) and their derivatives in a Tetra Pak® biochar was the leading target of this study. It was also evaluated the toxicity of Tetra Pak® biochars originated from pyrolysis performed at different temperatures. The relationship between the pyrolysis temperature and the yield of PAHs contained in Tetra Pak® biochars was also investigated. The material (Tetra Pak® packages, aseptic type) was decomposed in a laboratory pyrolysis reaction unit at different temperatures (400 °C, 500 °C, 600 °C, 700 °C). The concentrations of PAHs in Tetra Pak® biochars were determined using the method of pyrolysis gas chromatography combined with mass spectrometric detection. The toxicity of Tetra Pak® biochars was evaluated by Sinapis alba test and calculating of toxic equivalents.The total PAHs concentration in Tetra Pak® biochars oscillated between 79.6 mg/kg and 173.0 mg/kg. The measured concentrations of 16 priority PAHs U.S. Environmental Protection Agency (US EPA) reached the range from 38.4 mg/kg to 73.7 mg/kg. The yields of methylated derivatives of Tetra Pak®-biochar-borne PAHs varied from 5.2 mg/kg to 77.1 mg/kg. A phytotoxicity index of Sinapis alba has shown that biochar produced at temperatures above 500 °C is more likely to have a stimulating effect, supported by the leaching of Ca after the thermal decomposition of calcite and water extractable organic carbon. The stimulating effect of the addition of Tetra Pak® biochar increases with the decreasing concentration of biochar-borne PAHs. Given the financial cost and the minimisation of environmental risk, the addition of biochar in the range of 5–10% can be recommended.

Thermal destruction of polymers: analysis of the process physicochemical parameters

This experimental study has confirmed that during thermal decomposition of polymeric waste samples at a temperature of 850 °C, without oxygen access, there is a 90 % drop in the mass of this waste with the release of a large volume of gaseous products. This feature should be taken into consideration in the engineering calculations of reaction chambers, reactors, and connecting gas pipelines. The analytical study was carried out by a method of thermodynamic analysis using the universal estimation system Astra (TERRA). It has been shown that with an increase in reaction temperature there is a change in the composition of the products of thermal destruction of polymeric waste by reducing the mole fraction of СН4 and increasing the proportion of Н2. The calorific value was calculated according to Mendeleev’s empirical formula. The experimental study (a pyrolysis-gas chromatography method) has confirmed the calculation results regarding an increase in the proportion of hydrogen in the gaseous products of destruction with an increase in process temperature. As a result, due to the lower volumetric heat of hydrogen combustion, the total caloric content of the synthesis gas obtained is significantly reduced. For the experiments, a laboratory installation of low-temperature pyrolysis of polymers with external supply of thermal energy was built, and synthesis gas was used as an energy carrier. At the experimental-industrial installation, by a low-temperature pyrolysis method, the synthesis gas of a stable composition with a lower heat of combustion of 24.8 kJ/m3 was obtained. The reliability of the results of the proposed estimation method to the results of instrumental measurements has been shown. Promising areas of further studies have been determined, including the optimization of processes of thermal destruction of chlorine-containing polymer waste; the effective use of hydrogen from the composition of the synthesis gas obtained.

Experimental analysis of waste polyurethane from household appliances and its utilization possibilities

Polyurethane has a good insulation characteristic, and it is widely used as an insulation and lining material for refrigerators. Nevertheless, at the end of a product's lifetime, serious problems arise related to waste management. Recently, energy recovery has been marked as a promising solution, especially, waste-to-energy applications. To find an appropriate application for such waste, a thermal analysis was performed. An experimental analysis of polyurethane (PU) waste material was performed by the method of pyrolysis gas chromatography with mass spectrometric detection (Py-GC/MS) at various pyrolytic temperatures, namely, at 500, 600 and 700 °C. Waste polyurethane foam was conducted to investigations in the form of a bulk sample and sorted grain-size samples with a goal to detect the chemical composition of the pyrolysate. The investigation revealed various groups of organic compounds such as heterocyclic compounds of nitrogen and simple and polycyclic aromatic hydrocarbons, while notable concentrations of compounds containing chlorine were detected as well. The experimental analysis found differences in the composition of amines and other compounds and in the dependence on grain size composition. Bulk samples produced the highest concentration of amines (˃ 40%) at a temperature of 500 °C. The sample homogenization led to a significant increase in amines production. Polyurethane waste of grain size from 0.125 to 0.25 mm contained approximately 80% amines. The pyrolysis of the bulk sample at 600 °C yielded only 24% nitrogen heterocyclic compounds, while from the sorted grain-size <0.045 mm and 0.045–0.063 mm, yields were increased to 47.4 and 45.7%, respectively.

ON THE ORIGIN OF NATURAL BITUMEN AT YASNOYE-8 (SAKHALIN ISLAND)

In this study, we analyze samples of a black substance that was used for restoring a Tym-type vessel at Yasnoye-8, Central Sakhalin. On the basis of similar fi nds from the Japanese archipelago, it was initially assumed to be natural bitumen. However, science-based methods have not been previously used to test this assumption. In addition to the identifi cation of natural bitumen, we sought to identify its source. The study was carried out independently at two laboratories, using geochemical and petrographic methods, so the results can be considered reliable. For the fi rst time in Russia, the method of pyrolysis gas chromatography – mass spectrometry was used, along with elemental and petrographic analysis, to identify hydrocarbon from an archaeological site. The results confi rm the use of natural bitumen during the Early Iron Age. It can be procured in suffi cient amounts on Sakhalin Island. Identifi cation of specifi c sources is complicated by the virtually complete lack of geological data (bitumen is not mined for industrial purposes). Available materials suggest that bitumen found at Yasnoye-8 originates from the northern Sakhalin petroleum zone or from adjacent areas. No relationship to bitumen deposits in northeastern Honshu was found. Nor is it likely that the sample is related to superfi cial hydrocarbons of Hokkaido.

Evaluation of acidic paper deterioration in library materials by pyrolysis-gas chromatography

Pyrolysis-gas chromatography (Py-GC) has been applied to the evaluation of the deteriorated acidic paper in old books. A tiny piece (ca. 0.25 mg) of deteriorated paper was subjected to Py-GC measurement at 300 °C pyrolysis temperature. Levoglucosan and its dehydrated form levoglucosenone were typical degradation products while a recent control paper gave rise mainly to levoglucosan. The relative yield of levoglucosenone was much higher for the paper sample taken at the heavily deteriorated marginal part than that in the center of the same page of the old book. Accordingly, levoglucosenone observed in the pyrogram can be used as a marker to evaluate the degree of the deterioration of the acidic paper. The formation of levoglucosenone can be attributed to the slow deterioration process of paper, in which dehydration reaction play an important roll accompanied by the chain scission of cellulose. The Py-GC method for paper evaluation was also applied to clarify the effect of storage conditions and chemical compositions of paper materials to their deterioration processes.

Quantitative analysis of detailed lignin monomer composition by pyrolysis-gas chromatography combined with preliminary acetylation of the samples.

Detailed quantitative analysis of lignin monomer composition comprising p-coumaryl, coniferyl, and sinapyl alcohol and p-coumaraldehyde, coniferaldehyde, and sinapaldehyde in plant has not been studied from every point mainly because of artifact formation during the lignin isolation procedure, partial loss of the lignin components inherent in the chemical degradative methods, and difficulty in the explanation of the complex spectra generally observed for the lignin components. Here we propose a new method to quantify lignin monomer composition in detail by pyrolysis-gas chromatography (Py-GC) using acetylated lignin samples. The lignin acetylation procedure would contribute to prevent secondary formation of cinnamaldehydes from the corresponding alcohol forms during pyrolysis, which are otherwise unavoidable in conventional Py-GC process to some extent. On the basis of the characteristic peaks on the pyrograms of the acetylated sample, lignin monomer compositions in various dehydrogenative polymers (DHP) as lignin model compounds were determined, taking even minor components such as cinnamaldehydes into consideration. The observed compositions by Py-GC were in good agreement with the supplied lignin monomer contents on DHP synthesis. The new Py-GC method combined with sample preacetylation allowed us an accurate quantitative analysis of detailed lignin monomer composition using a microgram order of extractive-free plant samples.

Pyrolysis-mass spectrometry analysis of dehydrogenation lignin polymers with various syringyl/guaiacyl ratios

The present paper describes the application of pyrolysis-mass spectrometry (PYMS) to the analyses of lignocellulosic materials. Dehydrogenation lignin polymers (DHPs) with various syringyl/guaiacyl (S/G) ratios, and a standard, milled wood lignin from Aesculus turbinata Blume, were pyrolyzed at 500 °C for 4 s and the volatile products were ionized by low-voltage (20 eV) electron impact. The PYMS spectra of the lignins are shown with identification of most mass peaks. Of the observed mass peaks, the intensitities of the monomeric peaks corresponding to monomethoxyphenols (m/z 124, 137, 138 and 180) and dimethoxyphenols (m/z 154, 167, 182 and 210) were sensitive to the S/G ratio shifts of the DHPs. Changes in the monomeric mass peak intensities reflected those in the yields of the corresponding products determined by pyrolysis-gas chromatography (PYGC). The S/G pryolytic ratios, calculated from the summed mass peak intensities of syringyl and guaiacyl monomeric products, showed a linear correlation with syringaldehyde/vanillin (S/V) ratios determined by nitrobenzene oxidation. This finding suggested that the S/V ratios of lignocellulosic materials are predicted from the S/G pyrolytic ratios obtained by PYMS. Similar linear correlations were observed also between the S/G pyrolytic ratios determined by PYGC and the S/V ratios, for the DHPs and for Japanese hardwoods. Unlike the PYGC method, however, the PYMS method does not need time-consuming determinations of the response factor of each product to a flame ionization detector. This advantage may outweigh the inherent problems of PYMS, such as the ambiguous structural assignment of the mass peaks in the quantitative PYMS analyses of lignocellulosic materials. The dimeric mass peaks, which were hardly detected in an analytical system with a gas chromatograph, also contributed to the mass spectra. © 1997 John Wiley & Sons, Ltd.

Analysis of wool fiber by alkali-catalyzed pyrolysis gas chromatography

Alkali-catalyzed pyrolysis gas chromatography (PyGC) has been used to identify minute samples of wool fiber. The wool sample to which aqueous sodium hydroxide was added was pyrolyzed in a Curie-point pyrolyzer attached to a gas Chromatograph or a gas chromatograph-mass spectrometer. The addition of an aqueous solution of sodium hydroxide increased the production of specific volatile pyrolysis products from the constitutive amino acid residues of wool protein, i.e. acetaldehyde from alanine or proline, isobutyronitrile from valine, 2-methylbutyronitrile from isoleucine, isovaleronitrile from leucine and toluene from phenylalanine. Compared with conventional non-catalyzed PyGC, the alkali-catalyzed PyGC was found to greatly improve the detection limit of wool fiber and make it possible to analyze very minute samples. The alkali-catalyzed PyGC presented here has been shown to be applicable to minute thermally-denatured samples of wool fiber which cannot be identified successfully by morphological inspection using a microscope or by using Fourier-transform infrared microspectroscopy. Furthermore, the present PyGC method was successfully used for several protein samples and was shown to be useful for analysis of proteins other than wool fibers by using different special pyrograms reflecting different amino acid compositions.

Composition and structure analysis of styrene—maleic anhydride copolymer by pyrolysis-gas chromatography

A pyrolysis-gas chromatography method has been developed to study composition and microstructure of a styrene-maleic anhydride (SMA) copolymer. Since the anhydride functional group is not stable under normal pyrolysis conditions, a derivatization technique has been developed to successfully study the composition and microstructure. Because of the unique structure of SMA copolymers, the number average sequence length can be used to indicate the polymer chain length or average molecular mass. The method developed in this report has demonstrated a feasible approach to studying the composition and structure by pyrolysis-GC for those polymers containing functional groups which are not stable under pyrolysis conditions.

Composition and Microstructure Analysis of Chlorinated Polyethylene by Pyrolysis Gas Chromatography and Pyrolysis Gas Chromatography/Mass Spectrometry

A pyrolysis gas chromatography method was developed to determine the composition and microstructure of chlorinated polyethylene (CPE). This method utilized specific aromatic compounds which were formed through dehydrochlorination of trimers after pyrolysis of CPE polymers at elevated temperatures. The composition and microstructure calculation was based on the difference between the levels of ethylene and vinyl chloride trimers formed. This method is valid for CPE polymers containing between 25 and 48 wt % chlorine. The composition of CPE polymers used in this study was corroborated with 13C-NMR results and the manufacturer's product specification.

Confirmation by Pyrolysis-Gas Chromatography of the Absence of Polyvinylpyrrolidone in Beer Treated with Cross-Linked Polyvinylpyrrolidone

A pyrolysis-gas chromatography method was developed for the determination of residual polyvinylpyrrolidone (PVP) in beers that had been treated with cross-linked PVP for the removal of chill haze. ...

Structure Determination of Polymeric Materials by Pyrolysis Gas Chromatography

A pyrolysis gas chromatography method has been developed to investigate the microstructure of emulsion polymers. The number-average sequence length, which reflects the monomer arrangement in the polymer, was calculated using the proper formulas that incorporate the pure trimer peak intensities and hybrid trimer peak intensities. In this study, styrene and n-butyl acrylate copolymer systems were used to measure the degree of structure (i.e., the number-average sequence length for styrene and n-butyl acrylate repeat units) and compared to a homogeneous nonstructured (or random) copolymer. The number-average sequence length information was further extended to calculate the composition. For the emulsion polymers examined in this study, the composition elucidated from the number-average sequence length matched the preparation recipe and/or what was measured by 13 C NMR.

Determination of sulfur in biologically important substances by pyrolysis-gas chromatography

An analytical method for the determination of sulfur in biologically important substances has been developed using pyrolysis-gas chromatography (Py-GC) equipped with a flame photometric detector (FPD). This method is based on the determination of dimethyl sulfide (CH 3SCH 3) and hydrogen sulfide (H 2S), each of which is one of the pyrolysis products of the sulfur compounds contained in protein. The protein sample was pyrolyzed instantaneously at high temperature (590 °C) in a stream of nitrogen gas. The Py-GC method developed in the present study does not require any pretreatment and the analysis time for determining sulfur in biological samples is as quick as 30 min. The sulfur detection limit of this method was 40 ng for methionine and 60 ng for cystine and cysteine. The coefficient of variation was 5.7, 11 and 14% for methionine, cystine and cysteine, respectively. The determination of sulfur in biologically important substances such as human hair, dog hair, silk, etc. was carried out by the proposed Py-GC method. The analytical results revealed that sulfur is 3.3–4.3 wt.% in human hair and 2.4–3.5 wt.% in dog hair.

Thermal analysis as a method of investigation of polymer-polymer interaction

The method of pyrolysis gas chromatography and thermovolumetric thermal analysis has been used for the investigation of polyamic acid-poly- N-vinylpyrrolidone and polyinude-poly- N-vinylpyrrolidone mixtures in helium. The products of thermal degradation have been identified. Data of analysis of gaseous and liquid degradation products for individual polymers and mixtures indicate that the mechanism of thermal degradation of polyimide changes when poly- N-vinylpyrrolidone is introduced into the mixture. This change is caused by the existence of the polymer-polymer interaction between the components of the mixture.

Improved method of pyrolysis-gas chromatography for the determination of the yield of volatile components from coal

Presentation d'une methode de pyrolyse eclair d'une suspension de charbon finement broye dans l'eau pour la mesure de la teneur en matiere volatile du charbon. Precision de la methode

Characterization of styrene–acrylonitrile copolymer by pyrolysis gas chromatography

AbstractSamples of styrene–acrylonitrile (SAN) copolymer of different compositions, molecular weights, block copolymers, and a blend of styrene and acrylonitrile homopolymers were prepared and characterized by the method of pyrolysis gas chromatography. On decomposition of SAN copolymer samples at 645°C, eleven components were identified, the most important of them being styrene, acrylonitrile, and propionitrile. By examination of the pyrolyzate composition during pyrolysis of the SAN copolymer of different compositions, it was established that the propionitrile yield was definitely decreased when the acrylonitrile concentration in copolymer was about 60 mole‐%. Further, from the propionitrile yield, we could distinguish random SAN copolymer from the styrene‐acrylonitrile homopolymer blend, and on the basis of propionitrile yield some information on the molecular structure of the copolymer could be obtained. The styrene yield depends linearly on the copolymer composition. This permits determination of copolymer composition on the basis of the styrene yield. Furthermore, the effects of decomposition temperature and of molecular weight on the yields of styrene and acrylonitrile were examined.