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Publications (10 of 32) Show all publications
Eriksson, M., Sandström, K., Carlborg, M. & Broström, M. (2024). Impact of limestone surface impurities on quicklime product quality. Minerals, 14(3), Article ID 244.
Open this publication in new window or tab >>Impact of limestone surface impurities on quicklime product quality
2024 (English)In: Minerals, E-ISSN 2075-163X, Vol. 14, no 3, article id 244Article in journal (Refereed) Published
Abstract [en]

Quicklime is produced through the thermal processing of limestone in industrial kilns. During quarry operations, fine particulate quarry dust adheres to limestone lump surfaces, increasing the bulk concentration of impurities in limestone products. During thermal processing in a kiln, impurities such as Si, Mg, Al, Fe, and Mn react with Ca, reducing quicklime product quality. Which reactant phases are formed, and the extent to which these result in a reduction in quality, has not been extensively investigated. The present study investigated as-received and manually washed limestone product samples from two operational quarries using elemental compositions and a developed predictive multi-component chemical equilibrium model to obtain global phase diagrams for 1000–1500 °C, corresponding to the high-temperature zone of a lime kiln, identifying phases expected to be formed in quicklime during thermal processing. The results suggest that impurities found on the surface of the lime kiln limestone feed reduce the main quality parameter of the quicklime products, i.e., calcium oxide, CaO (s), content by 0.8–1.5 wt.% for the investigated materials. The results also show that, in addition to the effect of impurities, the quantity of CaO (s) varies greatly with temperature. More impurities result in more variation and a greater need for accurate temperature control of the kiln, where keeping the temperature below approximately 1300 °C, that of Hatrurite formation, is necessary for a product with higher CaO (s).

Place, publisher, year, edition, pages
MDPI, 2024
Keywords
calcium oxide, chemical equilibrium calculations, thermal process chemistry
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-223093 (URN)10.3390/min14030244 (DOI)2-s2.0-85189068374 (Scopus ID)
Funder
Swedish Energy Agency, 50224-1Vinnova, 2015-04541
Available from: 2024-04-11 Created: 2024-04-11 Last updated: 2024-05-02Bibliographically approved
Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2023). High temperature interactions between coal ash and MgO-based refractories in lime kiln conditions. Fuel, 342, Article ID 127711.
Open this publication in new window or tab >>High temperature interactions between coal ash and MgO-based refractories in lime kiln conditions
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2023 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 342, article id 127711Article in journal (Refereed) Published
Abstract [en]

Magnesium oxide (MgO)-based refractories are commonly used in quicklime and cement rotary kilns. At the high temperatures in the kiln burn zone, the infiltration of molten fuel ash into the refractory can occur. Subsequent chemical interactions can cause refractory wear that inflicts high maintenance costs and loss of production. To improve refractory reliability, it is necessary to increase the understanding of the interactions between fuel ash slag and refractory liner materials. Three commercially available MgO-based refractory materials were exposed to coal ash at 1200 °C and 1400 °C for between 15 and 60 min under a CO2-rich gaseous environment. Hot slag from the coal ash infiltrated the refractories and the infiltration depths were estimated with scanning electron microscope with energy dispersive X-ray spectroscopy. Based on detailed elemental and microstructure analyses, the interactions between ash and refractory were examined. Molten silicates infiltrated the refractory through grain boundaries and pores into depths of up to 2.8 mm. Powder X-ray diffraction of the exposed refractory samples indicated that MgO grains reacted with SiO2-containing phases to form Mg2SiO4. This was identified as a corrosion product whose formation was supported by thermochemical equilibrium calculations. Elevated Mg content was found in the ash residue on top of the samples, indicating the dissolution or dislocation of refractory components. In addition, phases such as MgO were identified in the ash residue.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Coal ash, Lime kilns, MgO refractory, Refractory corrosion, Silicate slag, Slag infiltration
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-205464 (URN)10.1016/j.fuel.2023.127711 (DOI)000952980900001 ()2-s2.0-85149015295 (Scopus ID)
Funder
Bio4EnergySwedish Energy Agency
Available from: 2023-03-07 Created: 2023-03-07 Last updated: 2023-11-15Bibliographically approved
Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2023). High temperature interactions between K-rich biomass ash and MgO-based refractories. Journal of the European Ceramic Society, 43(8), 3770-3777
Open this publication in new window or tab >>High temperature interactions between K-rich biomass ash and MgO-based refractories
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2023 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 43, no 8, p. 3770-3777Article in journal (Refereed) Published
Abstract [en]

MgO-based refractories are used in lime kilns to withstand the high temperature and chemical environment. Efforts to reduce CO2 emissions have led to an increased interest to use bio-based fuels as alternatives to traditional fossil sources. The potential for refractory corrosion from a potassium-rich biomass ash was investigated by studying the infiltration of olive pomace ash into magnesia/spinel refractories. Refractory samples were exposed to the ash at up to 1400 °C for 15–60 min in a CO2–rich atmosphere. Molten ash infiltrated the refractories through pores and grain boundaries to a depth of up to 9.6 mm, which was quantified with a new systematic procedure. The phase KAlO2 was identified inside the refractories after exposure, indicating an attack of spinel components by potassium. Phases found in the ash residues also indicated the migration of refractory constituents. Thermochemical equilibrium calculations were also used to investigate the ash/refractory chemistry.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Biomass ash; Lime kiln; Magnesia; Olive pomace; Potassium; Refractory corrosion; Slag infiltration
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-205465 (URN)10.1016/j.jeurceramsoc.2023.01.058 (DOI)000955011500001 ()2-s2.0-85148748148 (Scopus ID)
Funder
Bio4EnergySwedish Energy Agency, 34721-3Swedish Energy Agency, 47198-1
Available from: 2023-03-07 Created: 2023-03-07 Last updated: 2023-11-15Bibliographically approved
Miranda, D. A., Marín, K., Sundman, O., Hedenström, M., Quillaguaman, J., Gorzsás, A., . . . Martin, C. (2023). Production and characterization of poly(3-hydroxybutyrate) from Halomonas boliviensis LC1 cultivated in hydrolysates of quinoa stalks. Fermentation, 9(6), Article ID 556.
Open this publication in new window or tab >>Production and characterization of poly(3-hydroxybutyrate) from Halomonas boliviensis LC1 cultivated in hydrolysates of quinoa stalks
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2023 (English)In: Fermentation, E-ISSN 2311-5637, Vol. 9, no 6, article id 556Article in journal (Refereed) Published
Abstract [en]

The global production of fossil-based plastics has reached critical levels, and their substitution with bio-based polymers is an urgent requirement. Poly(3-hydroxybutyrate) (PHB) is a biopolymer that can be produced via microbial cultivation, but efficient microorganisms and low-cost substrates are required. Halomonas boliviensis LC1, a moderately halophilic bacterium, is an effective PHB producer, and hydrolysates of the residual stalks of quinoa (Chenopodium quinoa Willd.) can be considered a cheap source of sugars for microbial fermentation processes in quinoa-producing countries. In this study, H. boliviensis LC1 was adapted to a cellulosic hydrolysate of quinoa stalks obtained via acid-catalyzed hydrothermal pretreatment and enzymatic saccharification. The adapted strain was cultivated in hydrolysates and synthetic media, each of them with two different initial concentrations of glucose. Cell growth, glucose consumption, and PHB formation during cultivation were assessed. The cultivation results showed an initial lag in microbial growth and glucose consumption in the quinoa hydrolysates compared to cultivation in synthetic medium, but after 33 h, the values were comparable for all media. Cultivation in hydrolysates with an initial glucose concentration of 15 g/L resulted in a higher glucose consumption rate (0.15 g/(L h) vs. 0.14 g/(L h)) and volumetric productivity of PHB (14.02 mg/(L h) vs. 10.89 mg/(L h)) than cultivation in hydrolysates with 20 g/L as the initial glucose concentration. During most of the cultivation time, the PHB yield on initial glucose was higher for cultivation in synthetic medium than in hydrolysates. The produced PHBs were characterized using advanced analytical techniques, such as high-performance size-exclusion chromatography (HPSEC), Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). HPSEC revealed that the molecular weight of PHB produced in the cellulosic hydrolysate was lower than that of PHB produced in synthetic medium. TGA showed higher thermal stability for PHB produced in synthetic medium than for that produced in the hydrolysate. The results of the other characterization techniques displayed comparable features for both PHB samples. The presented results show the feasibility of producing PHB from quinoa stalks with H. boliviensis.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
adaptation, agricultural residues, biopolymers, Halomonas boliviensis, halophilic bacteria, lignocellulosic materials, polyhydroxybutyrate, quinoa
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-212048 (URN)10.3390/fermentation9060556 (DOI)001017168000001 ()2-s2.0-85163753314 (Scopus ID)
Funder
Swedish Research Council, 2016-05822Bio4Energy
Available from: 2023-07-18 Created: 2023-07-18 Last updated: 2023-07-18Bibliographically approved
Kumar Wagri, N., Carlborg, M., Eriksson, M., Ma, C., Broström, M. & Andersson, B. M. (2022). Interaction of olive pomace ash and coal ash with magnesium oxide based refractories. 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 The 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 >>Interaction of olive pomace ash and coal ash with magnesium oxide based refractories
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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 (Other academic)
Abstract [en]

In quicklime production, limestone is calcined at temperatures above 1000°C, depending on the desired product quality. Heat is supplied to the process from combustion inside the kilns that are insulated to reduce heat loss. The kilns are lined with insulating refractory bricks to withstand the hot, chemically aggressive, and mechanically abrasive environment. Magnesia bricks have emerged as well-performinglining materials, but they are still prone to extensive wear in kilns that are operated at higher temperatures. In particular, refractory corrosion can be caused by fuel ash infiltration that results inmaterial wear, which can incur high maintenance and operational costs through unplanned shutdowns of the kilns. At the same time, to reduce the release of fossil-based carbon to the atmosphere, it is of interest to introduce bio-based fuels into the kilns with only relatively small modifications to the process. Biobased waste streams from existing industries are preferable rather than biomass grown with the sole purpose of combustion. The ash content and properties of these types of waste residues do, however, tend to be problematic from a fuel ash chemistry point of view. Therefore, before introducing a new fuel, their potential effects on kiln lining material should be investigated. In this study, the infiltration of olivepomace ash and coal ash into commercially available refractory materials composed of mainly periclase(MgO) with minor amounts of spinel (MgAl2O4) were compared. They were exposed to the fuel ashes under a simulated lime kiln high CO2 atmosphere at 1200 and 1400°C for 15 and 60 minutes. The morphology and elemental composition of the exposed samples were investigated with scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. Ash-forming elements infiltrated the porous parts of the materials. The analytical results are complemented with thermodynamic equilibrium calculations to investigate the ash melting behavior. Crystalline phases in the residual ashes were investigated with X-ray diffraction. Refractory phases could be found in both ashes, indicating migration of refractory constituents. Olive pomace ash formed new crystalline compounds together with the refractory components whereas this was not observed for the coal ash, indicating that the former is more of a risk for material failure.  

Place, publisher, year, edition, pages
Department of Applied Physics and Electronics, Umeå University, 2022
Keywords
Coal ash, Olive pomace ash, MgO refractory, Corrosion, Slag intrusion, Potassium
National Category
Chemical Engineering
Identifiers
urn:nbn:se:umu:diva-199686 (URN)
Conference
The 28th International Conference on the Impact of Fuel Quality on Power Production and the Environment, Åre, Sweden, September 19-23, 2022
Note

Session 11. Non-Power Processes I. 

Proceedings published on USB. 

Available from: 2022-09-26 Created: 2022-09-26 Last updated: 2023-03-07Bibliographically 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
Sepman, A., Thorin, E., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. M. (2022). Laser-based detection of methane and soot during entrained-flow biomass gasification. Combustion and Flame, 237, Article ID 111886.
Open this publication in new window or tab >>Laser-based detection of methane and soot during entrained-flow biomass gasification
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2022 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 237, article id 111886Article in journal (Refereed) Published
Abstract [en]

Methane is one of the main gas species produced during biomass gasification and may be a desired or undesired product. Syngas CH4 concentrations are typically >5 vol-% (when desired) and 1–3 vol-% even when efforts are made to minimize it, while thermochemical equilibrium calculations (TEC) predict complete CH4 decomposition. How CH4 is generated and sustained in the reactor core is not well understood. To investigate this, accurate quantification of the CH4 concentration during the process is a necessary first step. We present results from rapid in situ measurements of CH4, soot volume fraction, H2O and gas temperature in the reactor core of an atmospheric entrained-flow biomass gasifier, obtained using tunable diode laser absorption spectroscopy (TDLAS) in the near-infrared (1.4 µm) and mid-infrared (3.1 µm) region. An 80/20 wt% mixture of forest residues and wheat straw was converted using oxygen-enriched air (O2>21 vol%) as oxidizer, while the global air-fuel equivalence ratio (AFR) was set to values between 0.3 and 0.7. Combustion at AFR 1.3 was performed as a reference. The results show that the CH4 concentration increased from 1 to 3 vol-% with decreasing AFR, and strongly correlated with soot production. In general, the TDLAS measurements are in good agreement with extractive diagnostics at the reactor outlet and TEC under fuel-lean conditions, but deviate significantly for lower AFR. Detailed 0D chemical reaction kinetics simulations suggest that the CH4 produced in the upper part of the reactor at temperatures >1700 K was fully decomposed, while the CH4 in the final syngas originated from the pyrolysis of fuel particles at temperatures below 1400 K in the lower section of the reactor core. It is shown that the process efficiency was significantly reduced due to the C and H atoms bound in methane and soot.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Entrained-flow reactor, Gasification, Biomass, Methane, Soot, Tunable diode laser absorption spectroscopy (TDLAS)
National Category
Energy Engineering Renewable Bioenergy Research Atom and Molecular Physics and Optics Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-190099 (URN)10.1016/j.combustflame.2021.111886 (DOI)000735780800001 ()2-s2.0-85120458898 (Scopus ID)
Funder
EU, Horizon Europe, 637020Swedish Energy Agency, 50470-1Bio4Energy
Available from: 2021-12-06 Created: 2021-12-06 Last updated: 2023-09-05Bibliographically approved
Chambi, D., Lundqvist, J., Nygren, E., Romero-Soto, L., Marin, K., Gorzsás, A., . . . Martín, C. (2022). Production of Exopolysaccharides by Cultivation of Halotolerant Bacillus atrophaeus BU4 in Glucose-and Xylose-Based Synthetic Media and in Hydrolysates of Quinoa Stalks. Fermentation, 8(2), Article ID 79.
Open this publication in new window or tab >>Production of Exopolysaccharides by Cultivation of Halotolerant Bacillus atrophaeus BU4 in Glucose-and Xylose-Based Synthetic Media and in Hydrolysates of Quinoa Stalks
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2022 (English)In: Fermentation, E-ISSN 2311-5637, Vol. 8, no 2, article id 79Article in journal (Refereed) Published
Abstract [en]

A halotolerant, exopolysaccharide-producing bacterium isolated from the Salar de Uyuni salt flat in Bolivia was identified as Bacillus atrophaeus using next-generation sequencing. Comparisons indicate that the genome most likely (p-value: 0.0024) belongs to a subspecies previously not represented in the database. The growth of the bacterial strain and its ability to produce exopolysaccharides (EPS) in synthetic media with glucose or xylose as carbon sources, and in hydrolysates of quinoa stalks, was investigated. The strain grew well in all synthetic media, but the growth in glucose was better than that in xylose. Sugar consumption was better when initial concentrations were low. The growth was good in enzymatically produced cellulosic hydrolysates but was inhibited in hemicellulosic hydrolysates produced using hydrothermal pretreatment. The EPS yields were up to 0.064 g/g on initial glucose and 0.047 g/g on initial xylose, and was higher in media with relatively low sugar concentrations. The EPS was isolated and purified by a sequential procedure including centrifugation, cold ethanol precipitation, trichloroacetic acid treatment, dialysis, and freeze-drying. Glucose and mannose were the main sugars identified in hydrolyzed EPS. The EPS was characterized by size-exclusion chromatography, Fouriertransform infrared (FTIR) spectroscopy, heteronuclear single-quantum coherence nuclear magnetic resonance (HSQC NMR) spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. No major differences were elucidated between EPS resulting from cultivations in glucoseor-xylose-based synthetic media, while some divergences with regard to molecular-weight averages and FTIR and HSQC NMR spectra were detected for EPS from hydrolysate-based media.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
Bacillus atrophaeus, Exopolysaccharide, Genome sequencing, Halotolerant bacterium, Lignocellulose bioconversion, Quinoa stalk
National Category
Bioprocess Technology
Identifiers
urn:nbn:se:umu:diva-192785 (URN)10.3390/fermentation8020079 (DOI)000871905700001 ()2-s2.0-85124840517 (Scopus ID)
Available from: 2022-03-02 Created: 2022-03-02 Last updated: 2023-09-05Bibliographically approved
Thorin, E., Sepman, A., Ögren, Y., Ma, C., Carlborg, M., Wennebro, J., . . . Schmidt, F. (2022). Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier. Proceedings of the Combustion Institute
Open this publication in new window or tab >>Quantitative real-time in situ measurement of gaseous K, KOH and KCl in a 140 kW entrained-flow biomass gasifier
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2022 (English)In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704Article in journal (Refereed) In press
Abstract [en]

Photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) was used to simultaneously measure the concentrations of gas phase atomic potassium (K), potassium hydroxide (KOH) and potassium chloride (KCl) in the reactor core of a 140 kWth atmospheric entrained-flow gasifier (EFG). In two gasification experiments at air-to-fuel equivalence ratio of 0.5, the EFG was first run on forest residues (FR) and then on an 80/20 mixture of FR and wheat straw (FR/WS). Combustion at air-to-fuel equivalence ratio of 1.3 was investigated for comparison. A high K(g) absorbance was observed in gasification, requiring the photofragmentation signals from KOH(g) and KCl(g) to be recorded at a fixed detuning of 7.3 cm−1 from the center of the K(g) absorption profile. In combustion, the fragments recombined instantly after the UV pulse within around 10 µs, whereas in gasification, the K(g) fragment concentration first increased further for 30 µs after the UV pulse, before slowly decaying for up to hundreds of µs. According to 0D reaction kinetics simulations, this could be explained by a difference in recombination kinetics, which is dominated by oxygen reactions in combustion and by hydrogen reactions in gasification. The K species concentrations in the EFG were stable on average, but periodic short-term variations due to fuel feeding were observed, as well as a gradual increase in KOH(g) over the day as the reactor approached global equilibrium. A comparison of the average K species concentrations towards the end of each experiment showed a higher total K in the gas phase for FR/WS, with higher K(g) and KCl(g), but lower KOH(g), compared to the FR fuel. The measured values were in reasonable agreement with predictions by thermodynamic equilibrium calculations.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Biomass, Entrained-flow gasification, Potassium (K), Photofragmentation, Tunable diode laser absorption spectroscopy (TDLAS)
National Category
Other Physics Topics Atom and Molecular Physics and Optics Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-199816 (URN)10.1016/j.proci.2022.07.180 (DOI)001019037700001 ()2-s2.0-85139508080 (Scopus ID)
Funder
Bio4EnergyThe Kempe Foundations, JCK-1316Swedish Energy Agency, 50470-1Swedish Energy Agency, 36160-1EU, Horizon 2020, 637020
Available from: 2022-09-29 Created: 2022-09-29 Last updated: 2023-09-05
Latham, K. G., Kozyatnyk, I., Figueira, J., Carlborg, M., Rosenbaum, E. & Jansson, S. (2021). Self-generation of low ash carbon microspheres from the hydrothermal supernatant of anaerobic digestate: Formation insights and supercapacitor performance. Chemical Engineering Journal Advances, 6, Article ID 100097.
Open this publication in new window or tab >>Self-generation of low ash carbon microspheres from the hydrothermal supernatant of anaerobic digestate: Formation insights and supercapacitor performance
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2021 (English)In: Chemical Engineering Journal Advances, E-ISSN 2666-8211, Vol. 6, article id 100097Article in journal (Refereed) Published
Abstract [en]

This work provides the first observations of and insights into the self-generation of carbon microspheres from the supernatant after hydrothermal carbonization of anaerobic digestate has been completed and the hydrochar removed. Solid State NMR and XPS revealed that the carbon microspheres were comprised of decomposed fragments of proteins, carbohydrates and lignin. The carbon microspheres were significantly lower in ash content (3.1%), compared to the hydrothermal solid (41.2%) and precursor (25.2%) and their formation reduced the total organic carbon load of the supernatant. The low ash content allowed them to be easily activated, achieving a surface area of 1711.0 m2 g−1, compared to 51.4 m2 g−1 for the activated hydrothermal solid and 12.8 m2 g−1 for the activated precursor. The microcarbon spheres achieved a specific capacitance from cyclic voltammetry of 86 F g−1 at 100 mV s−1 to 176 F g−1 at 1 mV s−1, while the gravimetric capacitance was 42 F g−1 at 25 A g−1 and 140 F g−1 at 0.5 A g−1 in 0.5 M Li2SO4 and a 1.8V potential window. Overall, this study highlights the importance of exploring this new product and its valorisation potential for the hydrothermal carbonization of ash-rich precursors.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Electrochemical capacitors, Hydrochar, Sediment, Solid state NMR, Wet waste materials
National Category
Other Chemistry Topics Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-202953 (URN)10.1016/j.ceja.2021.100097 (DOI)2-s2.0-85112574865 (Scopus ID)
Available from: 2023-01-14 Created: 2023-01-14 Last updated: 2023-03-07Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1170-2203

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