| 1. |
- Bonturi, Nemailla, et al.
(författare)
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Single Cell Oil Producing Yeasts Lipomyces starkeyi and Rhodosporidium toruloides : Selection of Extraction Strategies and Biodiesel Property Prediction
- 2015
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 8:6, s. 5040-5052
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Tidskriftsartikel (refereegranskat)abstract
- Single cell oils (SCOs) are considered potential raw material for the production of biodiesel. Rhodosporidium sp. and Lipomyces sp. are good candidates for SCO production. Lipid extractability differs according to yeast species and literature on the most suitable method for each oleaginous yeast species is scarce. This work aimed to investigate the efficiency of the most cited strategies for extracting lipids from intact and pretreated cells of Rhodosporidium toruloides and Lipomyces starkeyi. Lipid extractions were conducted using hexane or combinations of chloroform and methanol. The Folch method resulted in the highest lipid yields for both yeasts (42% for R. toruloides and 48% for L. starkeyi). Also, this method eliminates the cell pretreatment step. The Bligh and Dyer method underestimated the lipid content in the tested strains (25% for R. toruloides and 34% for L. starkeyi). Lipid extractability increased after acid pretreatment for the Pedersen, hexane, and Bligh and Dyer methods. For R. toruloides unexpected fatty acid methyl esters (FAME) composition were found for some lipid extraction strategies tested. Therefore, this work provides useful information for analytical and process development aiming at biodiesel production from the SCO of these two yeast species.
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| 2. |
- Kalogiannis, Konstantinos G., et al.
(författare)
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Aromatics from Beechwood Organosolv Lignin through Thermal and Catalytic Pyrolysis
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- Biomass fractionation, as an alternative to biomass pretreatment, has gained increasing research attention over the past few years as it provides separate streams of cellulose, hemicellulose, and lignin. These streams can be used separately and can provide a solution for improving the economics of emerging biorefinery technologies. The sugar streams are commonly used in microbial conversions, whereas during recent years lignin has been recognized as a valuable compound as it is the only renewable and abundant source of aromatic chemicals. Successfully converting lignin into valuable chemicals and products is key in achieving both environmental and economic sustainability of future biorefineries. In this work, lignin retrieved from beechwood sawdust delignification pretreatment via an organosolv process was depolymerized with thermal and catalytic pyrolysis. ZSM-5 commercial catalyst was used in situ to upgrade the lignin bio-oil vapors. Lignins retrieved from different modes of organosolv pretreatment were tested in order to evaluate the effect that upstream pretreatment has on the lignin fraction. Both thermal and catalytic pyrolysis yielded oils rich in phenols and aromatic hydrocarbons. Use of ZSM-5 catalyst assisted in overall deoxygenation of the bio-oils and enhanced aromatic hydrocarbons production. The oxygen content of the bio-oils was reduced at the expense of their yield. Organosolv lignins were successfully depolymerized towards phenols and aromatic hydrocarbons via thermal and catalytic pyrolysis. Hence, lignin pyrolysis can be an effective manner for lignin upgrading towards high added value products
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| 3. |
- Matsakas, Leonidas, et al.
(författare)
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High-Titer Methane from Organosolv-Pretreated Spruce and Birch
- 2017
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- The negative impact of fossil fuels and the increased demand for renewable energy sources has led to the use of novel raw material sources. Lignocellulosic biomass could serve as a possible raw material for anaerobic digestion and production of biogas. This work is aimed at using forest biomass, both softwood (spruce) and hardwood (birch), as a raw material for anaerobic digestion. We examined the effect of different operational conditions for the organosolv pretreatment (ethanol content, duration of treatment, and addition of acid catalyst) on the methane yield. In addition, we investigated the effect of addition of cellulolytic enzymes during the digestion. We found that inclusion of an acid catalyst during organosolv pretreatment improved the yields from spruce, but it did not affect the yields from birch. Shorter duration of treatment was advantageous with both materials. Methane yields from spruce were higher with lower ethanol content whereas higher ethanol content was more beneficial for birch. The highest yields obtained were 185 mL CH4/g VS from spruce and 259.9 mL CH4/g VS from birch. Addition of cellulolytic enzymes improved these yields to 266.6 mL CH4/g VS and 284.2 mL CH4/g VS, respectively.
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| 4. |
- Mesfun, Sennai, et al.
(författare)
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Technoeconomic assessment of hybrid organosolv-steam explosion pretreatment of woody biomass
- 2019
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 12:21
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates technoeconomic performance of standalone biorefinery concepts that utilize hybrid organic solvent and steam explosion pretreatment technique. The assessments were made based on a mathematical process model developed in UniSim Design software using inhouse experimental data. The work was motivated by successful experimental applications of the hybrid pretreatment technique on lignocellulosic feedstocks that demonstrated high fractionation efficiency into a cellulose-rich, a hemicellulose-rich and lignin streams. For the biorefinery concepts studied here, the targeted final products were ethanol, organosolv lignin and hemicellulose syrup. Minimum ethanol selling price (MESP) and Internal rate of return (IRR) were evaluated as economic indicators of the investigated biorefinery concepts. Depending on the configuration, and allocating all costs to ethanol, MESP in the range 0.53-0.95 €/L were required for the biorefinery concepts to break even. Under the assumed ethanol reference price of 0.55 €/L, the corresponding IRR were found to be in the range -1.75-10.7%. Hemicellulose degradation and high steam demand identified as major sources of inefficiencies for the process and economic performance, respectively. Sensitivity of MESP and IRR towards the most influential technical, economic and market parameters performed. © 2019 by the authors.
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| 5. |
- Nitsos, Christos, et al.
(författare)
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Organosolv fractionation of softwood biomass for biofuel and biorefinery applications
- 2018
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Softwoods represent a significant fraction of the available lignocellulosic biomass for conversion into a variety of bio-based products. Its inherent recalcitrance, however, makes its successful utilization an ongoing challenge. In the current work the research efforts for the fractionation and utilization of softwood biomass with the organosolv process are reviewed. A short introduction into the specific challenges of softwood utilization, the development of the biorefinery concept, as well as the initial efforts for the development of organosolv as a pulping method is also provided for better understanding of the related research framework. The effect of organosolv pretreatment at various conditions, in the fractionation efficiency of wood components, enzymatic hydrolysis and bioethanol production yields is then discussed. Specific attention is given in the effect of the pretreated biomass properties such as residual lignin on enzymatic hydrolysis. Finally, the valorization of organosolv lignin via the production of biofuels, chemicals, and materials is also described.
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| 6. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
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Single-Cell Oils from Oleaginous Microorganisms as Green Bio-Lubricants : Studies on Their Tribological Performance
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:20
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Tidskriftsartikel (refereegranskat)abstract
- Biolubricants refer to eco-friendly, biodegradable, and non-toxic lubricants. Their applications are still limited compared to mineral oils; however, their sustainable credentials are making them increasingly attractive. Vegetable oils are frequently used for this purpose. However, vegetable oils have issues of low lipid productivity, dependence on climatic conditions, and need for agricultural land. Microbial oils represent a more sustainable alternative. To ensure their widespread applicability, the suitability of microbial oils from a physicochemical point of view needs to be de-termined first. In this study, oils obtained from various oleagenic microbes—such as microalgae, thraustochytrids, and yeasts—were characterized in terms of their fatty acid profile, viscosity, friction coefficient, wear, and thermal stability. Oleaginous microalgal strains (Auxenochlorella protothe-coides and Chlorella sorokiniana), thraustochytrids strains (Aurantiochytrium limacinum SR21 and Au-rantiochytrium sp. T66), and yeast strains (Rhodosporidium toruloides and Cryptococcus curvatus) synthesized 64.5%, 35.15%, 47.89%, 47.93%, 56.42%, and 52.66% of lipid content, respectively. Oils from oleaginous microalgae (A. protothecoides and C. sorokiniana) and yeasts (R. toruloides and C. curvatus) possess excellent physicochemical and tribological qualities due to high amount of monounsatu-rated fatty acids (oleic acid C18:1 content, 56.38%, 58.82%, 46.67%, 38.81%) than those from oleaginous thraustochytrids (A. limacinum SR21 and Aurantiochytrium sp. T66; 0.96%, 0.08%, respectively) supporting their use as renewable and biodegradable alternatives to traditional mineral oil-based lubricants. Oil obtained from microalgae showed a lower friction coefficient than oils obtained from yeasts and thraustochytrids.
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| 7. |
- Cayenne, Aadila, et al.
(författare)
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Enhancing the Methane Yield of Salicornia spp. via Organosolv Fractionation as Part of a Halophyte Biorefinery Concept
- 2024
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Ingår i: Energies. - : Multidisciplinary Digital Publishing Institute (MDPI). - 1996-1073. ; 17:5
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Tidskriftsartikel (refereegranskat)abstract
- The present research investigated the effect of organosolv pretreatment on two species of salt-tolerant Salicornia spp. biomass, Salicornia dolichostachya and Salicornia ramosissima, for increasing biomethane production through anaerobic digestion. The final biomethane yield of de-juiced green fibers of Salicornia spp. from wet fractionation increased by 23–28% after organosolv treatment. The highest methane yield of about 300 mL-CH4/gVS was found after organosolv treatment with 60% v/v ethanol solution at 200 °C for 30 min, or at 180 °C for 30 or 60 min treatment time. Furthermore, the methane production rate increased significantly, reducing the time until 95% of the final methane yield was reached from 20 days to 6–10 days for the organosolv-treated biomass. This research shows that the process of anaerobic digestion of halophyte biomass benefits from cascade processing of Salicornia fibers in a biorefinery framework by sequential wet and organosolv fractionation for full utilization of halophytic biomass.
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| 8. |
- Patel, Alok, Dr. 1989-, et al.
(författare)
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Role of Oleaginous Microorganisms in the Field of Renewable Energy
- 2022
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 15:16
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The world increasingly requires biodegradable and renewable products in all production fields, with the vast volume of emissions generated by the fuel sector presenting a difficult issue that needs to be addressed [...]
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