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Selected papers from the latest issue:Analytical pyrolysis of humic substances from a Latosol (Typic Hapludox) under different land uses in Minas Gerais, Brazil
22 October 2011, 03:00:17
Publication year: 2011
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
Cristiane Pereira de Assis, José A. González-Pérez, José María de la Rosa, Ivo Jucksch, Eduardo de Sá Mendonça, ...
Humic acid (HA) and fulvic acid (FA) fractions isolated from a Humic Red-yellow Latosol (Typic Hapludox) under different land uses (forest, pasture, coffee) were studied by pyrolysis-gas matography–mass spectrometry (Py-GC/MS). Humic substances were extracted from soxhlet lipid free soil samples and the pyrolysis experiments consisted of a thermal desorption at sub-pyrolysis temperature (280 °C) followed by a flash pyrolysis (600 °C) on the same sample.Thermal desorption of HA and FA released mainly carbohydrate -derived compounds, N-compounds and series of alkanes. In surface samples most lignin- and carbohydrate-derived compounds are found weakly bounded to the HA structure indicating recent lignocellulosic contribution. In deeper dark soil layers the release of carbohydrate- derived moieties and N-compounds could indicate active iosynthesis by soil biota producing secondary biopolymers like chitin. Major compounds released after pyrolysis of HA were phenol and other benzene derivatives, whereas for FA aromatic and polyaromatic, N-containing and furan derivatives prevailed.In terms of land use the soils under pasture, FA became more aromatic and enriched in carbohydrate-derived compounds and the presence ofp-vinylguaiacol in the HA could indicate the contribution of lignin from grasses. In contrast, the coffee culture seems to favor the formation of FA with a more polyaromatic and phenolic structure. Most N-bearing compounds in HA and FA extracted from forest soil samples were released by desorption, indicating comparatively weaker bonds in their structure. This could be explained as a more recent contribution and/or comparatively rapid cycling of these organic substances in natural environments.With respect to the general dynamic of organic matter (OM) in the studied Oxisol, our results are compatible with the occurrence of a high biological activity associated with fast humification processes and the migration of oxidized OM, probably with soil cations as vectors.
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
Cristiane Pereira de Assis, José A. González-Pérez, José María de la Rosa, Ivo Jucksch, Eduardo de Sá Mendonça, ...
Humic acid (HA) and fulvic acid (FA) fractions isolated from a Humic Red-yellow Latosol (Typic Hapludox) under different land uses (forest, pasture, coffee) were studied by pyrolysis-gas matography–mass spectrometry (Py-GC/MS). Humic substances were extracted from soxhlet lipid free soil samples and the pyrolysis experiments consisted of a thermal desorption at sub-pyrolysis temperature (280 °C) followed by a flash pyrolysis (600 °C) on the same sample.Thermal desorption of HA and FA released mainly carbohydrate -derived compounds, N-compounds and series of alkanes. In surface samples most lignin- and carbohydrate-derived compounds are found weakly bounded to the HA structure indicating recent lignocellulosic contribution. In deeper dark soil layers the release of carbohydrate- derived moieties and N-compounds could indicate active iosynthesis by soil biota producing secondary biopolymers like chitin. Major compounds released after pyrolysis of HA were phenol and other benzene derivatives, whereas for FA aromatic and polyaromatic, N-containing and furan derivatives prevailed.In terms of land use the soils under pasture, FA became more aromatic and enriched in carbohydrate-derived compounds and the presence ofp-vinylguaiacol in the HA could indicate the contribution of lignin from grasses. In contrast, the coffee culture seems to favor the formation of FA with a more polyaromatic and phenolic structure. Most N-bearing compounds in HA and FA extracted from forest soil samples were released by desorption, indicating comparatively weaker bonds in their structure. This could be explained as a more recent contribution and/or comparatively rapid cycling of these organic substances in natural environments.With respect to the general dynamic of organic matter (OM) in the studied Oxisol, our results are compatible with the occurrence of a high biological activity associated with fast humification processes and the migration of oxidized OM, probably with soil cations as vectors.
Highlights
► Analytical pyrolysis (Py-GC/MS) was used to study humic (HA and FA) fractions isolated from a Latosol (Typic Hapludox) under different land uses (forest, pasture, coffee) ► In soil under pasture, FA was found more aromatic and enriched in carbohydrate-derived compounds. ► The coffee culture seems to favor the formation of FA with a more polyaromatic and phenolic structure ► Most N-bearing compounds were released by desorption, indicating weak bonds with HA and FA and a recent contribution and/or rapid cycling ► The results are compatible with the occurrence of fast humification processes and the migration of oxidized OM with soil cations as vectorsBEHAVIOUR OF SELECTED MAJOR ELEMENTS DURING FIXED-BED GASIFICATION OF SOUTH AFRICAN BITUMINOUS COAL
22 October 2011, 03:00:17
Publication year: 2011
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
J.R. Bunt, F.B. Waanders, H. Schobert
The Sasol-Lurgi Fixed Bed Dry Bottom gasifier (S-L FBDB) treats a feed coal containing c.a. 30% ash forming minerals, which means that there are complex mineralogical processes occurring simultaneously with each other, and in the gasification reactions, within the reactor. To obtain an understanding of the mineral transformational behaviour, a quenched commercial-scale S-L FBDB gasifier was sampled and characterized mineralogically. Crystalline phases measured by XRD analyses show the ash exiting the reactor contains anorthite, quartz, mullite, cristobalite, diopsite, mayenite, anhydrite, muscovite, hematite, and magnetite, with the non-crystalline proportion in the ash bed c.a. 53%. While many of the reactions in gasification are kinetically controlled, the equilibrium analysis using the Fact-Sage 5.3 modelling program provided a computational approach useful in supporting some, though not all, of the experimentally observed chemical and physical behaviour of elements in gasification. Interpretation of hypothetical model output results was of limited utility, since interstitial/matrix aluminosilicate glasses, which are known to form in practise, cannot be modelled at present because no thermodynamic data is available for these species in the Fact-Sage databases.
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
J.R. Bunt, F.B. Waanders, H. Schobert
The Sasol-Lurgi Fixed Bed Dry Bottom gasifier (S-L FBDB) treats a feed coal containing c.a. 30% ash forming minerals, which means that there are complex mineralogical processes occurring simultaneously with each other, and in the gasification reactions, within the reactor. To obtain an understanding of the mineral transformational behaviour, a quenched commercial-scale S-L FBDB gasifier was sampled and characterized mineralogically. Crystalline phases measured by XRD analyses show the ash exiting the reactor contains anorthite, quartz, mullite, cristobalite, diopsite, mayenite, anhydrite, muscovite, hematite, and magnetite, with the non-crystalline proportion in the ash bed c.a. 53%. While many of the reactions in gasification are kinetically controlled, the equilibrium analysis using the Fact-Sage 5.3 modelling program provided a computational approach useful in supporting some, though not all, of the experimentally observed chemical and physical behaviour of elements in gasification. Interpretation of hypothetical model output results was of limited utility, since interstitial/matrix aluminosilicate glasses, which are known to form in practise, cannot be modelled at present because no thermodynamic data is available for these species in the Fact-Sage databases.
Highlights
► We model the mineral transformation in a moving bed gasifier ► We dissect the contents of a quenched commercial-scale gasifier to validate the model ► XRD and XRF analysis results show low volatility of elements: Al, Si, Ti, Ca and Fe in agreement with model predictions.Characterization of Bio-Oil Recovered as Stage Fractions with Unique Chemical and Physical Properties
22 October 2011, 03:00:17
Publication year: 2011
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
A.S. Pollard, M.R. Rover, R.C. Brown
Bio-oil from fast pyrolysis of biomass consists of hundreds of compounds with a wide range of molecular weights. These include both volatile and non-volatile compounds and viscous oligomers, which complicates recovery of the liquid product from vapors and aerosols generated during pyrolysis. We have developed a bio-oil recovery system that overcomes the fouling problems that commonly occur in conventional condensers, allowing recovery of stage fractions (SF) of bio-oil with distinctive chemical and physical properties. The concept has been evaluated in an 8 kg/h process development unit (PDU) consisting of a fluidized bed pyrolyzer, hot cyclones, and a series of condensers and electrostatic precipitators (ESPs) that recover five stage fractions. Red oak was pyrolyzed in the PDU and the resulting stage fractions of bio-oil analyzed for moisture, modified acid number (MAN), water insoluble content, solids content, higher heating value (HHV), kinematic viscosity and chemical composition.
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
A.S. Pollard, M.R. Rover, R.C. Brown
Bio-oil from fast pyrolysis of biomass consists of hundreds of compounds with a wide range of molecular weights. These include both volatile and non-volatile compounds and viscous oligomers, which complicates recovery of the liquid product from vapors and aerosols generated during pyrolysis. We have developed a bio-oil recovery system that overcomes the fouling problems that commonly occur in conventional condensers, allowing recovery of stage fractions (SF) of bio-oil with distinctive chemical and physical properties. The concept has been evaluated in an 8 kg/h process development unit (PDU) consisting of a fluidized bed pyrolyzer, hot cyclones, and a series of condensers and electrostatic precipitators (ESPs) that recover five stage fractions. Red oak was pyrolyzed in the PDU and the resulting stage fractions of bio-oil analyzed for moisture, modified acid number (MAN), water insoluble content, solids content, higher heating value (HHV), kinematic viscosity and chemical composition.
Highlights
► A bio-oil recovery system was developed that recovers bio-oil as stage fractions ► The bio-oil stage fractions have distinctive chemical and physical properties ► The first two stages concentrated water soluble sugars and water insoluble “pyrolytic lignin” ► Most of the water and acetic acid traditionally found in bio-oil was driven to the last stage fractionPreparation and characterization of carbonaceous adsorbents from sewage sludge using a pilot-scale microwave heating equipment
22 October 2011, 03:00:17
Publication year: 2011
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
Q.H. Lin, H. Cheng, G.Y. Chen
Microwave heating technology is considered as a cost-effective alternative way for preparing activated carbon from organic solid wastes. In this study, a pilot-scale microwave heating apparatus with the processing capacity of 5 kg solid waste was constructed to prepare carbonaceous adsorbents from sewage sludge, and the effects of important microwave processing parameters and chemical activation treatments on the quality and yield of resultant carbonaceous adsorbents were investigated with the aim of technological industrialization. The surface properties and chemical compositions of the carbonaceous adsorbents were characterized using nitrogen adsorption, iodine adsorption, scanning electron microscopy, X-ray fluorescence, and Fourier-transform infrared spectroscopy. The microwave heating process could be clearly classed into three stages, i.e., drying, thermal desorption, and carbonization. The increase of carbonization temperature reduced the contents of oxygen-containing functional groups in sludge-based adsorbents. The optimum carbonization temperature was 600 °C, and a higher carbonization temperature (700 °C) gave rise to a detrimental impact on the quality of sludge-based adsorbents, in terms of specific surface area, total pore volume and iodine value. Activation treatment with KOH, ZnCl2and H3PO4achieved the better development of porous texture. The sludge-based adsorbent prepared via KOH activation at carbonization temperature of 600 °C presented the highest BET surface area of 130.7 m gand the highest total pore volume of 0.13 mL g. However, according to the results of batch adsorption experiment, the sludge-based adsorbents prepared via H3PO4activation acted as the best adsorbent to adsorb Cuand Pbfrom aqueous solutions.
Source: Journal of Analytical and Applied Pyrolysis, Available online 20 October 2011
Q.H. Lin, H. Cheng, G.Y. Chen
Microwave heating technology is considered as a cost-effective alternative way for preparing activated carbon from organic solid wastes. In this study, a pilot-scale microwave heating apparatus with the processing capacity of 5 kg solid waste was constructed to prepare carbonaceous adsorbents from sewage sludge, and the effects of important microwave processing parameters and chemical activation treatments on the quality and yield of resultant carbonaceous adsorbents were investigated with the aim of technological industrialization. The surface properties and chemical compositions of the carbonaceous adsorbents were characterized using nitrogen adsorption, iodine adsorption, scanning electron microscopy, X-ray fluorescence, and Fourier-transform infrared spectroscopy. The microwave heating process could be clearly classed into three stages, i.e., drying, thermal desorption, and carbonization. The increase of carbonization temperature reduced the contents of oxygen-containing functional groups in sludge-based adsorbents. The optimum carbonization temperature was 600 °C, and a higher carbonization temperature (700 °C) gave rise to a detrimental impact on the quality of sludge-based adsorbents, in terms of specific surface area, total pore volume and iodine value. Activation treatment with KOH, ZnCl2and H3PO4achieved the better development of porous texture. The sludge-based adsorbent prepared via KOH activation at carbonization temperature of 600 °C presented the highest BET surface area of 130.7 m gand the highest total pore volume of 0.13 mL g. However, according to the results of batch adsorption experiment, the sludge-based adsorbents prepared via H3PO4activation acted as the best adsorbent to adsorb Cuand Pbfrom aqueous solutions.
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