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The effect of redox conditions on sphagnum acid thermochemolysis product distributions in a northern peatland
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Eleanor Y. Swain , Geoffrey D. Abbott
Thermally assisted hydrolysis and methylation (THM) in the presence of tetramethylammonium hydroxide (TMAH) of a range of layers in eight peat cores from the Ryggmossen peatland (central Sweden) was carried out. This yielded a complex mixture including components I (methylated 4-isopropenylphenol (IUPAC name: 1-methoxy-4-(prop-1-en-2-yl)benzene)), IIa/b (methylated cis/trans 3-(4′-hydroxyphen-1-yl)but-2-enoic acid (IUPAC names: (E/Z)-methyl 3-(4-methoxyphenyl)but-2-enoate)) and III (methylated 3-(4′-hydroxyphen-1-yl)but-3-enoic acid (IUPAC name: methyl 3-(4-methoxyphenyl)but-3-enoate)) which have been assigned as products from “bound” sphagnum acid. The proportion of the individual sphagnum acid products relative to total Sphagnum yield revealed the simultaneous degradation of all four components in the unsaturated layer (which is characterised by oxic conditions) concomitant with the decrease of the total Sphagnum yield. Following their degradation in the surficial oxic layer, the total amounts of the sphagnum acid thermochemolysis products stabilise in the deeper seasonally saturated peat. With a further increase in burial depth, in the permanently saturated anoxic peat, the distribution of thermochemolysis products becomes dominated by I. The increase of σ I % relative to σ (IIa/b and III) % indicates that the mode of binding of sphagnum acid into the peat changes as a function of burial depth and hence position relative to the water table. Therefore the relative amounts of the four sphagnum acid THM products show some promise as indicators of redox conditions in young surficial peats.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Eleanor Y. Swain , Geoffrey D. Abbott
Thermally assisted hydrolysis and methylation (THM) in the presence of tetramethylammonium hydroxide (TMAH) of a range of layers in eight peat cores from the Ryggmossen peatland (central Sweden) was carried out. This yielded a complex mixture including components I (methylated 4-isopropenylphenol (IUPAC name: 1-methoxy-4-(prop-1-en-2-yl)benzene)), IIa/b (methylated cis/trans 3-(4′-hydroxyphen-1-yl)but-2-enoic acid (IUPAC names: (E/Z)-methyl 3-(4-methoxyphenyl)but-2-enoate)) and III (methylated 3-(4′-hydroxyphen-1-yl)but-3-enoic acid (IUPAC name: methyl 3-(4-methoxyphenyl)but-3-enoate)) which have been assigned as products from “bound” sphagnum acid. The proportion of the individual sphagnum acid products relative to total Sphagnum yield revealed the simultaneous degradation of all four components in the unsaturated layer (which is characterised by oxic conditions) concomitant with the decrease of the total Sphagnum yield. Following their degradation in the surficial oxic layer, the total amounts of the sphagnum acid thermochemolysis products stabilise in the deeper seasonally saturated peat. With a further increase in burial depth, in the permanently saturated anoxic peat, the distribution of thermochemolysis products becomes dominated by I. The increase of σ I % relative to σ (IIa/b and III) % indicates that the mode of binding of sphagnum acid into the peat changes as a function of burial depth and hence position relative to the water table. Therefore the relative amounts of the four sphagnum acid THM products show some promise as indicators of redox conditions in young surficial peats.
Highlights
► THM in the presence of TMAH liberated four Sphagnum phenols from surficial peat. ► Compare changes in distributions of four Sphagnum phenols as a function of peat depth. ► Changes in distributions of the Sphagnum phenols reflect redox conditions of the peat. ► Increased proportion of I relative to IIa/b and III reflects anoxia in surficial peats.Using Py-GC/MS to detect and measure silicone defoamers in pulp fibres and mill deposits
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Bruce Sithole , Chu Watanabe
Defoamers are often used to control or reduce foam problems in a variety of pulp and papermaking processes. It has been recognised that non-judicious use of defoamers can lead to undesirable deposition problems. Amide-based defoamers have been largely supplanted by waterbased or water-extended defoamers that are supposed to be non-depositing. However, mill experience and research has shown otherwise. Hence, there is a need for analytical procedures to determine silicone defoamer components in deposits. In this work, for the first time, Py-GC/MS has been used to analyse for silicone defoamers in pulp and paper matrices. This work demonstrates that the technique is ideal for analysis and characterisation of silicone defoamers on pulp fibres and in mill deposits. The technique is easier and much more rapid than using solvent extraction and solid phase extraction, previously developed for analysis of silicone oil defoamers in deposits. It is applicable to silicone defoamers irrespective of molecular weight and can be used to ascertain the source of a particular defoamer formulation. Application of the technique to a washed kraft pulp, previously treated with silicone defoamers, shows that silicone defoamer oil carryover on pulp fibres can be substantial, depending on the defoamer formulation used. In pitch deposits, the level of silicone oil can be over 25% (w/w). In addition, analysis of deposits from mills using the defoamers shows that silicone defoamers have the potential to cause pitch deposition contrary to claims that the defoamers do not cause such problems. Thus, the method can be used to assess the impact of defoamer carryover on pulp properties and the contribution of silicone defoamers to pitch deposition.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Bruce Sithole , Chu Watanabe
Defoamers are often used to control or reduce foam problems in a variety of pulp and papermaking processes. It has been recognised that non-judicious use of defoamers can lead to undesirable deposition problems. Amide-based defoamers have been largely supplanted by waterbased or water-extended defoamers that are supposed to be non-depositing. However, mill experience and research has shown otherwise. Hence, there is a need for analytical procedures to determine silicone defoamer components in deposits. In this work, for the first time, Py-GC/MS has been used to analyse for silicone defoamers in pulp and paper matrices. This work demonstrates that the technique is ideal for analysis and characterisation of silicone defoamers on pulp fibres and in mill deposits. The technique is easier and much more rapid than using solvent extraction and solid phase extraction, previously developed for analysis of silicone oil defoamers in deposits. It is applicable to silicone defoamers irrespective of molecular weight and can be used to ascertain the source of a particular defoamer formulation. Application of the technique to a washed kraft pulp, previously treated with silicone defoamers, shows that silicone defoamer oil carryover on pulp fibres can be substantial, depending on the defoamer formulation used. In pitch deposits, the level of silicone oil can be over 25% (w/w). In addition, analysis of deposits from mills using the defoamers shows that silicone defoamers have the potential to cause pitch deposition contrary to claims that the defoamers do not cause such problems. Thus, the method can be used to assess the impact of defoamer carryover on pulp properties and the contribution of silicone defoamers to pitch deposition.
Highlights
► We describe the first known application for detection and determination of silicone defoamers in pulp and paper matrices. ► Silicone defoamer formulations from different suppliers can be differentiated by Py-GC/MS. ► Contrary to claims, silicone defoamers adsorb significantly to pulp fibres and significant amounts remain after washing of the pulp. ► Some silicone defoamer formulations contain penta and tetra cyclic silicone components that may be a health hazard. ► Silicone defoamers can cause pitch deposition in pulp and paper making operations.Lao lacquer culture and history—Analysis of Lao lacquer wares
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Masako Miyazato , Rong Lu , Takayuki Honda , Tetsuo Miyakoshi
Four kinds of Lao lacquer wares were analyzed using a digital optical microscope, infrared, field emission scanning electron microscope with energy dispersive X-ray spectrometry, and pyrolysis gas chromatography–mass spectrometry. 3-Heptylphenol, 3-pentadecanylphenol, 3-(10-phenyldecyl)phenol, and 3-(12-phenyldodecyl)phenol, which belong to the characteristic pyrolysis products of thitsiol were detected in the mass chromatograms at m/z =108 of all the objects. In addition, some kind of natural resin was also detected. These results suggest that in the development of Lao lacquer history and culture, lacquer workers used the local lacquer resources to produce lacquer-ware, and learned to use natural resin in the restoration and protection of the lacquer-ware.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Masako Miyazato , Rong Lu , Takayuki Honda , Tetsuo Miyakoshi
Four kinds of Lao lacquer wares were analyzed using a digital optical microscope, infrared, field emission scanning electron microscope with energy dispersive X-ray spectrometry, and pyrolysis gas chromatography–mass spectrometry. 3-Heptylphenol, 3-pentadecanylphenol, 3-(10-phenyldecyl)phenol, and 3-(12-phenyldodecyl)phenol, which belong to the characteristic pyrolysis products of thitsiol were detected in the mass chromatograms at m/z =108 of all the objects. In addition, some kind of natural resin was also detected. These results suggest that in the development of Lao lacquer history and culture, lacquer workers used the local lacquer resources to produce lacquer-ware, and learned to use natural resin in the restoration and protection of the lacquer-ware.
Highlights
► Four kinds of Lao lacquer wares were analyzed. ► 3-Heptylphenol and 3-pentadecanylphenol which belongs to the characteristic pyrolysis products of thitsiol were detected. ► The results shown that Lao people have used local lacquer as an adhesive or coating material. ► During the restoration of lacquer wares, Lao people were also able to use natural resin efficiently.Physicochemical characterisation of torrefied biomass
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Raimie H.H. Ibrahim , Leilani I. Darvell , Jenny M. Jones , Alan Williams
Torrefaction is a mild pyrolysis treatment under inert atmosphere that has been found to improve the physical and chemical properties of biomass as a fuel. In this study, several wood fuels: willow, eucalyptus, a mixture of hardwoods (oak and birch) and a mixture of softwoods (pine, larch and spruce) were torrefied at 270 and 290°C with two residence times (30 and 60min). Physicochemical properties of the torrefied materials, such as grindability, density, hydrophobicity and surface area were investigated. Furthermore, information was also obtained from microscopic and spectrometric studies, namely transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), to gain an insight into any changes in morphology and chemical composition due to the treatments. Temperature plays a major role during torrefaction and choosing an optimum condition is fundamental to attaining a satisfactory energy yield. Results show the lower temperature and shorter residence time was the best treatment to achieve good physical properties with a relatively high energy yield. When treated at these conditions, the softwood mixture had the highest energy (95%), followed by the hardwood mixture (80%), then willow (79%), and finally eucalyptus (75%). Increasing the severity of the torrefaction conditions greatly improved the physical characteristics of the torrefied biomass, in terms of grindability properties and hydrophobicity. While little difference in porosity and surface area were detected by the methods used, the XPS and FTIR studies showed that torrefaction results in a decrease in the ROH groups and an increase in CO groups within the fuels. This results in a decrease in the affinity of the fuels to absorb water, and therefore improves their hydrophobicity. For all the fuels, there was a critical temperature for torrefaction, above which abrupt changes in many properties occurred. These include hydrophobicity, energy yield, and grindability. The critical temperatures were fuel dependent and therefore the results indicate that careful optimisation is required for all fuel types to maximise the benefits of torrefaction whilst maintaining a good energy yield.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Raimie H.H. Ibrahim , Leilani I. Darvell , Jenny M. Jones , Alan Williams
Torrefaction is a mild pyrolysis treatment under inert atmosphere that has been found to improve the physical and chemical properties of biomass as a fuel. In this study, several wood fuels: willow, eucalyptus, a mixture of hardwoods (oak and birch) and a mixture of softwoods (pine, larch and spruce) were torrefied at 270 and 290°C with two residence times (30 and 60min). Physicochemical properties of the torrefied materials, such as grindability, density, hydrophobicity and surface area were investigated. Furthermore, information was also obtained from microscopic and spectrometric studies, namely transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), to gain an insight into any changes in morphology and chemical composition due to the treatments. Temperature plays a major role during torrefaction and choosing an optimum condition is fundamental to attaining a satisfactory energy yield. Results show the lower temperature and shorter residence time was the best treatment to achieve good physical properties with a relatively high energy yield. When treated at these conditions, the softwood mixture had the highest energy (95%), followed by the hardwood mixture (80%), then willow (79%), and finally eucalyptus (75%). Increasing the severity of the torrefaction conditions greatly improved the physical characteristics of the torrefied biomass, in terms of grindability properties and hydrophobicity. While little difference in porosity and surface area were detected by the methods used, the XPS and FTIR studies showed that torrefaction results in a decrease in the ROH groups and an increase in CO groups within the fuels. This results in a decrease in the affinity of the fuels to absorb water, and therefore improves their hydrophobicity. For all the fuels, there was a critical temperature for torrefaction, above which abrupt changes in many properties occurred. These include hydrophobicity, energy yield, and grindability. The critical temperatures were fuel dependent and therefore the results indicate that careful optimisation is required for all fuel types to maximise the benefits of torrefaction whilst maintaining a good energy yield.
Highlights
► We study solid properties of torrefied willow, eucalyptus, softwood, hardwood. ► Changes in chemical groups upon torrefaction lead to hydrophobicity and grindability. ► Gradual changes in solid properties occur below a critical torrefaction temperature. ► Abrupt changes in solid properties occur above a critical torrefaction temperature. ► Optimisation maximises benefits of torrefaction whilst maintaining good energy yield.Thermochemolysis using TMAAc and TMAH reagents as means to differentiate between free acids and esters
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): T. Ohra-aho , J. Ropponen , T. Tamminen
The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): T. Ohra-aho , J. Ropponen , T. Tamminen
The reactivity of aromatic and aliphatic esters in on-line thermochemolysis in the presence of methylation reagents was studied using model compounds. Guaiacyl and 2-nonyl palmitates were synthesised, representing aromatic and aliphatic ester bonds, respectively. These model compounds were analysed by on-line thermochemolysis using tetramethylammonium acetate (TMAAc) and tetramethylammonium hydroxide (TMAH) in order to differentiate free acids from esterified acids. The released palmitic acid with TMAH for both model compounds was close to the theoretical palmitic acid content in the model compounds, even if part of the aliphatic ester had not reacted with TMAH. The free palmitic acid content by TMAAc was one third of the theoretical value for aromatic ester and only a few percentages for aliphatic ester. The result indicated that the less basic reagent is able to hydrolyse the aromatic ester linkage to some extent, whereas the aliphatic ester remains intact. Thus, differentiation of free acids by TMAAc from the esterified acids cannot be reliably performed from matrices containing aromatic esters. It was found that transesterification due to the use of methanol as a solvent with TMAAc is an insignificant reaction in on-line thermochemolysis.
Highlights
► The reactivity of aromatic and aliphatic esters in on-line thermochemolysis was studied. ► Guaiacyl palmitate and 2-nonyl palmitate represented the aromatic and aliphatic ester bonds, respectively. ► Total amount of acids can be determined by TMAH from samples containing aliphatic and aromatic ester. ► The aromatic ester bond is partly hydrolysed in the presence of less basic reagent TMAAc, whereas the aliphatic ester bond is stable against TMAAc.Analytical pyrolysis as an instrument to study the chemical transformations of hydrothermally modified wood
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Juris Grinins , Bruno Andersons , Vladimirs Biziks , Ingeborga Andersone , Galina Dobele
In the present study, changes in the chemical structure of the components of deciduous wood species, i.e., birch (Betula spp.), aspen (Populus tremula) and grey alder (Alnus incana) wood, after hydrothermal modification (HTM) were investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and wet chemical analysis. The objective of this study was to elucidate the chemical changes in HTM deciduous wood dependent on the treatment parameters using chemical analysis and analytical pyrolysis and to evaluate the differences between the tree species. The results of both chemical and analytical pyrolysis studies demonstrate the effect of HTM on the chemical composition of deciduous wood. Wet chemical analyses showed that the hemicellulose content in wood decreased considerably (by 60–75%), whereas the cellulose and lignin contents increased by 6–20% and ∼50%, respectively. The thermal destruction of hemicelluloses during HTM was also indicated by the water condensates, which contained acids and sugars. As a result of the HTM, wood transitions from a solid state to an aggregate state, in which the chemical composition of the gases (gas mixture) depends on the chemical composition of the wood. Py-GC/MS can quantitatively and promptly detect changes in the chemical composition of wood after HTM. As a result of the high HTM of wood above 160°C, hemicelluloses are thermochemically destroyed and the primary products are acids (e.g., acetic acid and formic acid). Cellulose and lignin are more thermally stable than the hemicelluloses, as evidenced by the analytical pyrolysis results, which showed that the hemicellulose content in the wood decreased and the lignin content increased by revealing that the acid, ester and ether content in the gases decreased (by 24–33%) and the guaiacyl and syringyl derivative content increased (by 5–7%). Analytical pyrolysis is a promising method for understanding chemical transformations in HTM wood.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Juris Grinins , Bruno Andersons , Vladimirs Biziks , Ingeborga Andersone , Galina Dobele
In the present study, changes in the chemical structure of the components of deciduous wood species, i.e., birch (Betula spp.), aspen (Populus tremula) and grey alder (Alnus incana) wood, after hydrothermal modification (HTM) were investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and wet chemical analysis. The objective of this study was to elucidate the chemical changes in HTM deciduous wood dependent on the treatment parameters using chemical analysis and analytical pyrolysis and to evaluate the differences between the tree species. The results of both chemical and analytical pyrolysis studies demonstrate the effect of HTM on the chemical composition of deciduous wood. Wet chemical analyses showed that the hemicellulose content in wood decreased considerably (by 60–75%), whereas the cellulose and lignin contents increased by 6–20% and ∼50%, respectively. The thermal destruction of hemicelluloses during HTM was also indicated by the water condensates, which contained acids and sugars. As a result of the HTM, wood transitions from a solid state to an aggregate state, in which the chemical composition of the gases (gas mixture) depends on the chemical composition of the wood. Py-GC/MS can quantitatively and promptly detect changes in the chemical composition of wood after HTM. As a result of the high HTM of wood above 160°C, hemicelluloses are thermochemically destroyed and the primary products are acids (e.g., acetic acid and formic acid). Cellulose and lignin are more thermally stable than the hemicelluloses, as evidenced by the analytical pyrolysis results, which showed that the hemicellulose content in the wood decreased and the lignin content increased by revealing that the acid, ester and ether content in the gases decreased (by 24–33%) and the guaiacyl and syringyl derivative content increased (by 5–7%). Analytical pyrolysis is a promising method for understanding chemical transformations in HTM wood.
Highlights
► Hydrothermal modification – modification in a saturated steam environment at superatmospheric pressure. ► The relative amount of hemicelluloses in the modified wood decreases, but that of cellulose and lignin increases. ► Hemicelluloses–the most thermally unstable component of the cell wall. ► Water condensate – a mixture of the products of thermal destruction of hemicelluloses. ► In lignin pyrolysis products, the content of compounds with a short aliphatic chain increases.Identification and classification of glucose-based polysaccharides by applying Py-GC/MS and SIMCA
14 August 2013,
07:12:23
Publication date: September
2013
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Valentina Becerra , Jürgen Odermatt , Martin Nopens
This paper describes a simplified method for the identification of glucose-based polymers (polysaccharides). The method developed consists of classifying the results from analytical pyrolysis gas chromatography mass spectrometry (Py-GC/MS) by applying soft independent modelling of class analogy (SIMCA). Since the amount of inorganic compounds in the sample influences the pyrolysis results, the classification model is applied to the pyrolysis results obtained from samples in their original form and after pre-treatment. The pre-treatment aims at removing the inorganic compounds from the polysaccharides and consists of washing out the samples with acid solutions. Depending on the acid used, pyrolysis results may differ. Therefore, the pre-treatment impact on the pyrolysis results is evaluated as well. After optimisation of the sample pre-treatment, it is possible to discriminate between various subgroups of starches (native, cationic, oxidised starches and dextrin). This indicates that appropriate sample pre-treatment in combination with chemometric data evaluation results in a clear classification of very similar samples showing very similar pyrograms. The methodology developed facilitates the analysis and identification of deposits originating from polysaccharides found in paper production processes.
Source:Journal of Analytical and Applied Pyrolysis, Volume 103
Author(s): Valentina Becerra , Jürgen Odermatt , Martin Nopens
This paper describes a simplified method for the identification of glucose-based polymers (polysaccharides). The method developed consists of classifying the results from analytical pyrolysis gas chromatography mass spectrometry (Py-GC/MS) by applying soft independent modelling of class analogy (SIMCA). Since the amount of inorganic compounds in the sample influences the pyrolysis results, the classification model is applied to the pyrolysis results obtained from samples in their original form and after pre-treatment. The pre-treatment aims at removing the inorganic compounds from the polysaccharides and consists of washing out the samples with acid solutions. Depending on the acid used, pyrolysis results may differ. Therefore, the pre-treatment impact on the pyrolysis results is evaluated as well. After optimisation of the sample pre-treatment, it is possible to discriminate between various subgroups of starches (native, cationic, oxidised starches and dextrin). This indicates that appropriate sample pre-treatment in combination with chemometric data evaluation results in a clear classification of very similar samples showing very similar pyrograms. The methodology developed facilitates the analysis and identification of deposits originating from polysaccharides found in paper production processes.
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