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Boman, Christoffer
Publications (10 of 105) Show all publications
García-López, N., Bargués-Tobella, A., Goodman, R. C., Uwingabire, S., Sundberg, C., Boman, C. & Nyberg, G. (2024). An integrated agroforestry-bioenergy system for enhanced energy and food security in rural sub-Saharan Africa. Ambio
Open this publication in new window or tab >>An integrated agroforestry-bioenergy system for enhanced energy and food security in rural sub-Saharan Africa
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2024 (English)In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209Article in journal (Refereed) Epub ahead of print
Abstract [en]

Most people in rural sub-Saharan Africa lack access to electricity and rely on traditional, inefficient, and polluting cooking solutions that have adverse impacts on both human health and the environment. Here, we propose a novel integrated agroforestry-bioenergy system that combines sustainable biomass production in sequential agroforestry systems with biomass-based cleaner cooking solutions and rural electricity production in small-scale combined heat and power plants and estimate the biophysical system outcomes. Despite conservative assumptions, we demonstrate that on-farm biomass production can cover the household’s fuelwood demand for cooking and still generate a surplus of woody biomass for electricity production via gasification. Agroforestry and biochar soil amendments should increase agricultural productivity and food security. In addition to enhanced energy security, the proposed system should also contribute to improving cooking conditions and health, enhancing soil fertility and food security, climate change mitigation, gender equality, and rural poverty reduction.

Keywords
Biochar, Cleaner cooking, Modern energy access, Restoration, Rural electrification through combined heat and power plants, Sustainable development
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-225945 (URN)10.1007/s13280-024-02037-0 (DOI)001236528400002 ()38822967 (PubMedID)2-s2.0-85195114204 (Scopus ID)
Available from: 2024-06-12 Created: 2024-06-12 Last updated: 2024-06-12
Uski, O., Rankin, G. D., Wingfors, H., Magnusson, R., Boman, C., Muala, A., . . . Sandström, T. (2024). In vitro toxicity evaluation in A549 cells of diesel particulate matter from two different particle sampling systems and several resuspension media. Journal of Applied Toxicology
Open this publication in new window or tab >>In vitro toxicity evaluation in A549 cells of diesel particulate matter from two different particle sampling systems and several resuspension media
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2024 (English)In: Journal of Applied Toxicology, ISSN 0260-437X, E-ISSN 1099-1263Article in journal (Refereed) Epub ahead of print
Abstract [en]

In urban areas, inhalation of fine particles from combustion sources such as diesel engines causes adverse health effects. For toxicity testing, a substantial amount of particulate matter (PM) is needed. Conventional sampling involves collection of PM onto substrates by filtration or inertial impaction. A major drawback to those methodologies is that the extraction process can modify the collected particles and alter their chemical composition. Moreover, prior to toxicity testing, PM samples need to be resuspended, which can alter the PM sample even further. Lastly, the choice of the resuspension medium may also impact the detected toxicological responses. In this study, we compared the toxicity profile of PM obtained from two alternative sampling systems, using in vitro toxicity assays. One system makes use of condensational growth before collection in water in an impinger – BioSampler (CG-BioSampler), and the other, a Dekati® Gravimetric Impactor (DGI), is based on inertial impaction. In addition, various methods for resuspension of DGI collected PM were compared. Tested endpoints included cytotoxicity, formation of cellular reactive oxygen species, and genotoxicity. The alternative collection and suspension methods affected different toxicological endpoints. The water/dimethyl sulfoxide mixture and cell culture medium resuspended particles, along with the CG-BioSampler sample, produced the strongest responses. The water resuspended sample from the DGI appeared least toxic. CG-BioSampler collected PM caused a clear increased response in apoptotic cell death. We conclude that the CG-BioSampler PM sampler is a promising alternative to inertial impaction sampling.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
apoptosis, diesel exhaust, extraction, impinger, particulate matter, reactive oxygen species, sampling, soot, toxicity
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:umu:diva-224261 (URN)10.1002/jat.4616 (DOI)001214370400001 ()38705171 (PubMedID)2-s2.0-85192155238 (Scopus ID)
Available from: 2024-05-14 Created: 2024-05-14 Last updated: 2024-05-14
Rahman, M., Upadhyay, S., Ganguly, K., Introna, M., Ji, J., Boman, C., . . . Palmberg, L. (2023). Comparable response following exposure to biodiesel and diesel exhaust particles in advanced multicellular human lung models. Toxics, 11(6), Article ID 532.
Open this publication in new window or tab >>Comparable response following exposure to biodiesel and diesel exhaust particles in advanced multicellular human lung models
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2023 (English)In: Toxics, E-ISSN 2305-6304, Vol. 11, no 6, article id 532Article in journal (Refereed) Published
Abstract [en]

Biodiesel is considered to be a sustainable alternative for fossil fuels such as petroleum-based diesel. However, we still lack knowledge about the impact of biodiesel emissions on humans, as airways and lungs are the primary target organs of inhaled toxicants. This study investigated the effect of exhaust particles from well-characterized rapeseed methyl ester (RME) biodiesel exhaust particles (BDEP) and petro-diesel exhaust particles (DEP) on primary bronchial epithelial cells (PBEC) and macrophages (MQ). The advanced multicellular physiologically relevant bronchial mucosa models were developed using human primary bronchial epithelial cells (PBEC) cultured at air–liquid interface (ALI) in the presence or absence of THP-1 cell-derived macrophages (MQ). The experimental set-up used for BDEP and DEP exposures (18 µg/cm2 and 36 µg/cm2) as well as the corresponding control exposures were PBEC-ALI, MQ-ALI, and PBEC co-cultured with MQ (PBEC-ALI/MQ). Following exposure to both BDEP and DEP, reactive oxygen species as well as the stress protein heat shock protein 60 were upregulated in PBEC-ALI and MQ-ALI. Expression of both pro-inflammatory (M1: CD86) and repair (M2: CD206) macrophage polarization markers was increased in MQ-ALI after both BDEP and DEP exposures. Phagocytosis activity of MQ and the phagocytosis receptors CD35 and CD64 were downregulated, whereas CD36 was upregulated in MQ-ALI. Increased transcript and secreted protein levels of CXCL8, as well as IL-6 and TNF-α, were detected following both BDEP and DEP exposure at both doses in PBEC-ALI. Furthermore, the cyclooxygenase-2 (COX-2) pathway, COX-2-mediated histone phosphorylation and DNA damage were all increased in PBEC-ALI following exposure to both doses of BDEP and DEP. Valdecoxib, a COX-2 inhibitor, reduced the level of prostaglandin E2, histone phosphorylation, and DNA damage in PBEC-ALI following exposure to both concentrations of BDEP and DEP. Using physiologically relevant multicellular human lung mucosa models with human primary bronchial epithelial cells and macrophages, we found BDEP and DEP to induce comparable levels of oxidative stress, inflammatory response, and impairment of phagocytosis. The use of a renewable carbon-neutral biodiesel fuel does not appear to be more favorable than conventional petroleum-based alternative, as regards of its potential for adverse health effects.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
biodiesel, COX-2, DNA damage, lung, MQ-ALI, oxidative stress, particles, PBEC-ALI, petro-diesel, PGE2, phagocytosis
National Category
Pharmacology and Toxicology
Identifiers
urn:nbn:se:umu:diva-212077 (URN)10.3390/toxics11060532 (DOI)001017713500001 ()37368632 (PubMedID)2-s2.0-85163637334 (Scopus ID)
Funder
Swedish Research Council, 2018-03233Swedish Fund for Research Without Animal ExperimentsSwedish Heart Lung Foundation
Available from: 2023-07-17 Created: 2023-07-17 Last updated: 2023-07-17Bibliographically approved
Hansson, A., Rankin, G., Uski, O., Sehlstedt, M., Pourazar, J., Lindgren, R., . . . Muala, A. (2023). Reduced bronchoalveolar macrophage phagocytosis and cytotoxic effects after controlled short-term exposure to wood smoke in healthy humans. Particle and Fibre Toxicology, 20(1), Article ID 30.
Open this publication in new window or tab >>Reduced bronchoalveolar macrophage phagocytosis and cytotoxic effects after controlled short-term exposure to wood smoke in healthy humans
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2023 (English)In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 20, no 1, article id 30Article in journal (Refereed) Published
Abstract [en]

Background: Exposure to wood smoke has been shown to contribute to adverse respiratory health effects including airway infections, but the underlying mechanisms are unclear. A preceding study failed to confirm any acute inflammation or cell influx in bronchial wash (BW) or bronchoalveolar lavage (BAL) 24 h after wood smoke exposure but showed unexpected reductions in leukocyte numbers. The present study was performed to investigate responses at an earlier phase, regarding potential development of acute inflammation, as well as indications of cytotoxicity.

Methods: In a double-blind, randomised crossover study, 14 healthy participants were exposed for 2 h to filtered air and diluted wood smoke from incomplete wood log combustion in a common wood stove with a mean particulate matter concentration of 409 µg/m3. Bronchoscopy with BW and BAL was performed 6 h after exposure. Differential cell counts, assessment of DNA-damage and ex vivo analysis of phagocytic function of phagocytosing BAL cells were performed. Wood smoke particles were also collected for in vitro toxicological analyses using bronchial epithelial cells (BEAS-2B) and alveolar type II-like cells (A549).

Results: Exposure to wood smoke increased BAL lactate dehydrogenase (LDH) (p = 0.04) and reduced the ex vivo alveolar macrophage phagocytic capacity (p = 0.03) and viability (p = 0.02) vs. filtered air. BAL eosinophil numbers were increased after wood smoke (p = 0.02), while other cell types were unaffected in BW and BAL. In vitro exposure to wood smoke particles confirmed increased DNA-damage, decreased metabolic activity and cell cycle disturbances.

Conclusions: Exposure to wood smoke from incomplete combustion did not induce any acute airway inflammatory cell influx at 6 h, apart from eosinophils. However, there were indications of a cytotoxic reaction with increased LDH, reduced cell viability and impaired alveolar macrophage phagocytic capacity. These findings are in accordance with earlier bronchoscopy findings at 24 h and may provide evidence for the increased susceptibility to infections by biomass smoke exposure, reported in population-based studies.

Place, publisher, year, edition, pages
BioMed Central (BMC), 2023
Keywords
Air pollution, Biomass combustion, Bronchoscopy, Controlled human exposure, Cytotoxicity, In vitro, Macrophages, Phagocytosis, Wood smoke
National Category
Respiratory Medicine and Allergy Dermatology and Venereal Diseases
Identifiers
urn:nbn:se:umu:diva-212714 (URN)10.1186/s12989-023-00541-x (DOI)37517998 (PubMedID)2-s2.0-85165871931 (Scopus ID)
Funder
Swedish Heart Lung FoundationVästerbotten County CouncilSwedish Energy AgencyUmeå University
Available from: 2023-08-15 Created: 2023-08-15 Last updated: 2023-08-15Bibliographically approved
Mukarunyana, B., Boman, C., Kabera, T., Lindgren, R. & Fick, J. (2023). The ability of biochars from cookstoves to remove pharmaceuticals and personal care products from hospital wastewater. Environmental Technology & Innovation, 32, Article ID 103391.
Open this publication in new window or tab >>The ability of biochars from cookstoves to remove pharmaceuticals and personal care products from hospital wastewater
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2023 (English)In: Environmental Technology & Innovation, ISSN 2352-1864, Vol. 32, article id 103391Article in journal (Refereed) Published
Abstract [en]

Adequate treatment of wastewater to remove micropollutants constitutes a major concern globally. Despite this, large volumes of untreated wastewater are released into the environment, mainly due to the cost involved. Biochars have been suggested to have the potential to remove pharmaceuticals and personal care products (PPCP) from wastewater, but, adsorption potential needs to be investigated further. Production of biochars should also preferably be sustainable and based on low-cost materials. This study investigated the ability of nine biochars produced in three cookstoves and from three feedstocks. All biochars were characterized and then applied in adsorption experiments, based on authentic hospital effluent. Our analytical method included 32 pharmaceuticals and personal care products, and 28 of these were detected and quantified in hospital wastewater effluent samples. Some PPCP were present in relatively high concentrations (more than 24 µg/L). Adsorption experiments showed that the biochars used in the investigation had average removal rates (RR) ranging from 14.2% to 65.5%. Removal rates also varied between and within cookstoves and feedstock. Although cookstove biochars with a low surface area in this study generally showed lower removal rates, results from surface characterization were not detailed enough to correlate the physicochemical properties of the pollutants with the adsorption. Further characterizations are therefore needed to point out the most important parameters involved in PPCP adsorption on cookstove biochars.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Biochar cookstove, Feedstock, Hospital wastewater, PPCPs, Removal rate
National Category
Environmental Sciences Water Treatment
Identifiers
urn:nbn:se:umu:diva-215394 (URN)10.1016/j.eti.2023.103391 (DOI)2-s2.0-85173621784 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Available from: 2023-10-27 Created: 2023-10-27 Last updated: 2023-10-27Bibliographically approved
Strandberg, A., Steinvall, E., Morari, A. & Boman, C. (2023). Time-resolved understanding of the conversion of biochar and its properties during gasification. In: : . Paper presented at Nordic Flame Days 2023, Trondheim, Norway, 29-30 November, 2023.
Open this publication in new window or tab >>Time-resolved understanding of the conversion of biochar and its properties during gasification
2023 (English)Conference paper, Oral presentation with published abstract (Other academic)
National Category
Chemical Process Engineering Energy Engineering Other Chemistry Topics
Identifiers
urn:nbn:se:umu:diva-219273 (URN)
Conference
Nordic Flame Days 2023, Trondheim, Norway, 29-30 November, 2023
Funder
ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 22-331J. Gust. Richert stiftelse, 2022-00816Bio4Energy, B4E3-FM-2-08
Available from: 2024-01-10 Created: 2024-01-10 Last updated: 2024-01-10Bibliographically approved
Hedayati, A., Falk, J., Boren, E., Lindgren, R., Skoglund, N., Boman, C. & Öhman, M. (2022). Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus. Energy & Fuels, 36(7), 3640-3653
Open this publication in new window or tab >>Ash Transformation during Fixed-Bed Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus
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2022 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 36, no 7, p. 3640-3653Article in journal (Refereed) Published
Abstract [en]

In this study, ash transformation during fixed-bed combustion of different agricultural opportunity fuels was investigated with a special focus on potassium (K) and phosphorus (P). The fuel pellets were combusted in an underfed fixed-bed pellet burner. Residual ashes (bottom ash and slag) and particulate matter were collected and characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography. The interpretation of the results was supported by thermodynamic equilibrium calculations. For all fuels, almost all P (>97%) was found in residual-/coarse ash fractions, while K showed different degrees of volatilization, depending on fuel composition. During combustion of poplar, which represents Ca-K-rich fuels, a carbonate melt rich in K and Ca decomposed into CaO, CO2, and gaseous K species at sufficiently high temperatures. Ca5(PO4)3OH was the main P-containing crystalline phase in the bottom ash. For wheat straw and grass, representing Si-K-rich fuels, a lower degree of K volatilization was observed than for poplar. P was found here in amorphous phosphosilicates and CaKPO4. For wheat grain residues, representing P-K-rich fuels, a high degree of both K and P retention was observed due to the interaction of K and P with the fuel-bed constituents, i.e., char, ash, and slag. The residual ash was almost completely melted and rich in P, K, and Mg. P was found in amorphous phosphates and different crystalline phases such as KMgPO4, K2CaP2O7, K2MgP2O7, and K4Mg4(P2O7)3. In general, the results therefore imply that an interaction between ash-forming elements in a single burning fuel particle and the surrounding bed ash or slag is important for the overall retention of P and K during fuel conversion in fixed-bed combustion of agricultural biomass fuels.

Keywords
Plant derived food, Redox reactions, Fuels, Particulate matter, Reaction products
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:umu:diva-193834 (URN)10.1021/acs.energyfuels.1c04355 (DOI)000797939400020 ()2-s2.0-85127329835 (Scopus ID)
Funder
Swedish Research Council Formas, 2017-01613Swedish Research Council, 2016-04380Swedish Research Council, 2017-05331Swedish Energy Agency, 41875-1
Available from: 2022-04-20 Created: 2022-04-20 Last updated: 2023-09-05Bibliographically approved
Borén, E., Lindgren, R., Carlborg, M., Skoglund, N. & Boman, C. (2022). Kaolin as fuel additive in grate combustion of biomass to mitigate ash related problems and particle emissions. In: Markus Broström (Ed.), Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment: . Paper presented at 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022. Department of Applied Physics and Electronics, Umeå University
Open this publication in new window or tab >>Kaolin as fuel additive in grate combustion of biomass to mitigate ash related problems and particle emissions
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2022 (English)In: Proceedings of the 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment / [ed] Markus Broström, Department of Applied Physics and Electronics, Umeå University , 2022Conference paper, Published paper (Refereed)
Abstract [en]

Bioenergy is a fundamental part in sustainable development but use of novel fuel feedstocks potentiallymore sustainable may also bring associated ash-related challenges in practical operation that could bemitigated by co-conversion or additives. Kaolin, a clay mineral, is an additive known to be beneficialfor reduction of slagging tendencies and particulate matter formation in combustion of traditionalwoody-type biomass but its impact on thermal conversion of other biomasses still warrantsinvestigation. The aim of the present work is therefore to investigate how thermal conversion of atypical K-Ca-rich woody-type biomass, poplar, and a K-Si-rich annual crop, grass, is affected by kaolinaddition in fixed bed combustion. Additivation levels were calculated according to amount of alkaliintroduced with the two feedstocks, and incorporated by co-pelletization, in the case of poplar, anadditional blending d method was tested, by powder coating of pellets The results show that kaolinaddition improved the bottom ash characteristics, especially for grass, but the main differencesbetween feedstocks were found in particulate matter and flue gas composition. The particulate matterconcentrations were reduced with kaolin addition due to removal of gaseous K compounds which inturn caused higher SOx and HCl concentrations due to the lower amount of gaseous alkali for reaction.Further, initially high CO levels observed for both fuel feedstocks were reduced with the addition ofkaolin where co-pelletization with poplar proved more effective than powder coating the fuel particlesurfaces. This suggests that high concentrations of gaseous K-compounds may impact conversion ofthe carbonaceous matrix negatively.

Place, publisher, year, edition, pages
Department of Applied Physics and Electronics, Umeå University, 2022
National Category
Energy Engineering Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-199710 (URN)
Conference
28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022
Funder
Bio4Energy
Note

Session 9. Ash Transformation. 

Proceedings published on USB. 

Available from: 2022-09-27 Created: 2022-09-27 Last updated: 2023-03-07Bibliographically approved
Unosson, J., Kabele, M., Boman, C., Nyström, R., Sadiktsis, I., Westerholm, R., . . . Bosson, J. A. (2021). Acute cardiovascular effects of controlled exposure to dilute Petrodiesel and biodiesel exhaust in healthy volunteers: a crossover study. Particle and Fibre Toxicology, 18(1), Article ID 22.
Open this publication in new window or tab >>Acute cardiovascular effects of controlled exposure to dilute Petrodiesel and biodiesel exhaust in healthy volunteers: a crossover study
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2021 (English)In: Particle and Fibre Toxicology, E-ISSN 1743-8977, Vol. 18, no 1, article id 22Article in journal (Refereed) Published
Abstract [en]

Background: Air pollution derived from combustion is associated with considerable cardiorespiratory morbidity and mortality in addition to environmental effects. Replacing petrodiesel with biodiesel may have ecological benefits, but impacts on human health remain unquantified.

The objective was to compare acute cardiovascular effects of blended and pure biodiesel exhaust exposure against known adverse effects of petrodiesel exhaust (PDE) exposure in human subjects.

In two randomized controlled double-blind crossover studies, healthy volunteers were exposed to PDE or biodiesel exhaust for one hour. In study one, 16 subjects were exposed, on separate occasions, to PDE and 30% rapeseed methyl ester biodiesel blend (RME30) exhaust, aiming at PM10 300 μg/m3. In study two, 19 male subjects were separately exposed to PDE and exhaust from a 100% RME fuel (RME100) using similar engine load and exhaust dilution. Generated exhaust was analyzed for physicochemical composition and oxidative potential. Following exposure, vascular endothelial function was assessed using forearm venous occlusion plethysmography and ex vivo thrombus formation was assessed using a Badimon chamber model of acute arterial injury. Biomarkers of inflammation, platelet activation and fibrinolysis were measured in the blood.

Results: In study 1, PDE and RME30 exposures were at comparable PM levels (314 ± 27 μg/m3; (PM10 ± SD) and 309 ± 30 μg/m3 respectively), whereas in study 2, the PDE exposure concentrations remained similar (310 ± 34 μg/m3), but RME100 levels were lower in PM (165 ± 16 μg/m3) and PAHs, but higher in particle number concentration. Compared to PDE, PM from RME had less oxidative potential. Forearm infusion of the vasodilators acetylcholine, bradykinin, sodium nitroprusside and verapamil resulted in dose-dependent increases in blood flow after all exposures. Vasodilatation and ex vivo thrombus formation were similar following exposure to exhaust from petrodiesel and the two biodiesel formulations (RME30 and RME100). There were no significant differences in blood biomarkers or exhaled nitric oxide levels between exposures.

Conclusions: Despite differences in PM composition and particle reactivity, controlled exposure to biodiesel exhaust was associated with similar cardiovascular effects to PDE. We suggest that the potential adverse health effects of biodiesel fuel emissions should be taken into account when evaluating future fuel policies.

Trial registration: ClinicalTrials.gov, NCT01337882/NCT01883466. Date of first enrollment March 11, 2011, registered April 19, 2011, i.e. retrospectively registered.

Place, publisher, year, edition, pages
BioMed Central (BMC), 2021
Keywords
Air pollution, Biodiesel, Cardiovascular system, Diesel, Endothelial function, Particulate matter, Thrombosis, Vascular function, Vasomotor dysfunction
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-186143 (URN)10.1186/s12989-021-00412-3 (DOI)000661490800001 ()34127003 (PubMedID)2-s2.0-85107933281 (Scopus ID)
Funder
AFA InsuranceSwedish Heart Lung FoundationWellcome trust, WT103782AIARegion Västerbotten
Available from: 2021-07-14 Created: 2021-07-14 Last updated: 2023-07-07Bibliographically approved
Hedayati, A., Lindgren, R., Skoglund, N., Boman, C., Kienzl, N. & Öhman, M. (2021). Ash Transformation during Single-Pellet Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus. Energy & Fuels, 35(2), 1449-1464
Open this publication in new window or tab >>Ash Transformation during Single-Pellet Combustion of Agricultural Biomass with a Focus on Potassium and Phosphorus
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2021 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 35, no 2, p. 1449-1464Article in journal (Refereed) Published
Abstract [en]

In this study, ash transformation and release of critical ash-forming elements during single-pellet combustion of different types of agricultural opportunity fuels were investigated. The work focused on potassium (K) and phosphorus (P). Single pellets of poplar, wheat straw, grass, and wheat grain residues were combusted in a macro-thermogravimetric analysis reactor at three different furnace temperatures (600, 800, and 950 °C). In order to study the transformation of inorganic matters at different stages of the thermal conversion process, the residues were collected before and after full devolatilization, as well as after complete char conversion. The residual char/ash was characterized by scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, inductively coupled plasma, and ion chromatography, and the interpretation of results was supported by thermodynamic equilibrium calculations. During combustion of poplar, representing a Ca-K-rich woody energy crop, the main fraction of K remained in the residual ash primarily in the form of K2Ca(CO3)2 at lower temperatures and in a K-Ca-rich carbonate melt at higher temperatures. Almost all P retained in the ash and was mainly present in the form of hydroxyapatite. For the Si-K-rich agricultural biomass fuels with a minor (wheat straw) or moderate (grass) P content, the main fraction of K remained in the residual ash mostly in K-Ca-rich silicates. In general, almost all P was retained in the residual ash both in K-Ca-P-Si-rich amorphous structures, possibly in phosphosilicate-rich melts, and in crystalline forms as hydroxyapatite, CaKPO4, and calcium phosphate silicate. For the wheat grain, representing a K-P-rich fuel, the main fraction of K and P remained in the residual ash in the form of K-Mg-rich phosphates. The results showed that in general for all studied fuels, the main release of P occurred during the devolatilization stage, while the main release of K occurred during char combustion. Furthermore, less than 20% of P and 35% of K was released at the highest furnace temperature for all fuels.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2021
National Category
Energy Engineering Bioenergy
Identifiers
urn:nbn:se:umu:diva-180458 (URN)10.1021/acs.energyfuels.0c03324 (DOI)000613197300044 ()2-s2.0-85100036140 (Scopus ID)
Available from: 2021-02-18 Created: 2021-02-18 Last updated: 2023-09-05Bibliographically approved
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