Change search
Link to record
Permanent link

Direct link
BETA
Publications (9 of 9) Show all publications
Raghavendran, V., Nitsos, C., Matsakas, L., Rova, U., Christakopoulos, P. & Olsson, L. (2018). A comparative study of the enzymatic hydrolysis of batch organosolv-pretreated birch and spruce biomass. AMB Express, 8(1), Article ID 114.
Open this publication in new window or tab >>A comparative study of the enzymatic hydrolysis of batch organosolv-pretreated birch and spruce biomass
Show others...
2018 (English)In: AMB Express, ISSN 2191-0855, E-ISSN 2191-0855, Vol. 8, no 1, article id 114Article in journal (Refereed) Published
Abstract [en]

A shift towards a sustainable and green society is vital to reduce the negative effects of climate change associated with increased CO2 emissions. Lignocellulosic biomass is both renewable and abundant, but is recalcitrant to deconstruction. Among the methods of pretreatment available, organosolv (OS) delignifies cellulose efficiently, significantly improving its digestibility by enzymes. We have assessed the hydrolysability of the cellulose-rich solid fractions from OS-pretreated spruce and birch at 2% w/v loading (dry matter). Almost complete saccharification of birch was possible with 80 mg enzyme preparation/gsolids (12 FPU/gsolids), while the saccharification yield for spruce was only 70%, even when applying 60 FPU/gsolids. As the cellulose content is enriched by OS, the yield of glucose was higher than in their steam-exploded counterparts. The hydrolysate was a transparent liquid due to the absence of phenolics and was also free from inhibitors. OS pretreatment holds potential for use in a large-scale, closed-loop biorefinery producing fuels from the cellulose fraction and platform chemicals from the hemicellulose and lignin fractions respectively.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-70136 (URN)10.1186/s13568-018-0643-y (DOI)000438255300003 ()29992363 (PubMedID)2-s2.0-85049690419 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-07-19 (inah)

Available from: 2018-07-19 Created: 2018-07-19 Last updated: 2018-09-14Bibliographically approved
Matsakas, L., Nitsos, C., Raghavendran, V., Yakimenko, O., Persson, G., Olsson, E., . . . Christakopoulos, P. (2018). A novel hybrid organosolv: steam explosion method for the efficient fractionation and pretreatment of birch biomass. Biotechnology for Biofuels, 11(1), Article ID 160.
Open this publication in new window or tab >>A novel hybrid organosolv: steam explosion method for the efficient fractionation and pretreatment of birch biomass
Show others...
2018 (English)In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 11, no 1, article id 160Article in journal (Refereed) Published
Abstract [en]

The main role of pretreatment is to reduce the natural biomass recalcitrance and thus enhance saccharification yield. A further prerequisite for efficient utilization of all biomass components is their efficient fractionation into well-defined process streams. Currently available pretreatment methods only partially fulfill these criteria. Steam explosion, for example, excels as a pretreatment method but has limited potential for fractionation, whereas organosolv is excellent for delignification but offers poor biomass deconstruction.

Results

In this article, a hybrid method combining the cooking and fractionation of conventional organosolv pretreatment with the implementation of an explosive discharge of the cooking mixture at the end of pretreatment was developed. The effects of various pretreatment parameters (ethanol content, duration, and addition of sulfuric acid) were evaluated. Pretreatment of birch at 200 °C with 60% v/v ethanol and 1% w/wbiomass H2SO4 was proven to be the most efficient pretreatment condition yielding pretreated solids with 77.9% w/w cellulose, 8.9% w/w hemicellulose, and 7.0 w/w lignin content. Under these conditions, high delignification of 86.2% was demonstrated. The recovered lignin was of high purity, with cellulose and hemicellulose contents not exceeding 0.31 and 3.25% w/w, respectively, and ash to be < 0.17% w/w in all cases, making it suitable for various applications. The pretreated solids presented high saccharification yields, reaching 68% at low enzyme load (6 FPU/g) and complete saccharification at high enzyme load (22.5 FPU/g). Finally, simultaneous saccharification and fermentation (SSF) at 20% w/w solids yielded an ethanol titer of 80 g/L after 192 h, corresponding to 90% of the theoretical maximum.

Conclusions

The novel hybrid method developed in this study allowed for the efficient fractionation of birch biomass and production of pretreated solids with high cellulose and low lignin contents. Moreover, the explosive discharge at the end of pretreatment had a positive effect on enzymatic saccharification, resulting in high hydrolyzability of the pretreated solids and elevated ethanol titers in the following high-gravity SSF. To the best of our knowledge, the ethanol concentration obtained with this method is the highest so far for birch biomass.

Place, publisher, year, edition, pages
BioMed Central, 2018
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-69455 (URN)10.1186/s13068-018-1163-3 (DOI)000434952000002 ()29930706 (PubMedID)2-s2.0-85048400180 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-06-13 (andbra)

Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-08-08Bibliographically approved
Nitsos, C., Matsakas, L., Triantafyllidis, K., Rova, U. & Christakopoulos, P. (2018). Investigation of different pretreatment methods of Mediterranean-type ecosystem agricultural residues: characterisation of pretreatment products, high-solids enzymatic hydrolysis and bioethanol production. Biofuels, 9(5), 545-558
Open this publication in new window or tab >>Investigation of different pretreatment methods of Mediterranean-type ecosystem agricultural residues: characterisation of pretreatment products, high-solids enzymatic hydrolysis and bioethanol production
Show others...
2018 (English)In: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277, Vol. 9, no 5, p. 545-558Article in journal (Refereed) Published
Abstract [en]

Agricultural and agro-industrial lignocellulosic residues represent an important renewable resource for the production of fuels and chemicals towards a bio-based economy. Olive pruning, vineyard pruning and almond shells are important residues from agricultural activities in Mediterranean-type ecosystems. In the current work, bioethanol production from the above three types of agro-residues was studied, focusing on the effect of different pretreatment methods on enzymatic saccharrification efficiency of cellulose and production of second-generation bioethanol. Dilute acid, hydrothermal and steam explosion pretreatments were compared in order to remove hemicellulose and facilitate the subsequent enzymatic hydrolysis of the hemicellulose-deficient biomass to glucose. Enzymatic hydrolysis was performed in a free-fall mixing reactor enabling high solids loading of 23% w/w. This allowed hydrolysis of up to 67% of available cellulose in almond shells and close to 50% in olive pruning samples, and facilitated high ethanol production in the subsequent fermentation step; the highest ethanol concentrations achieved were 47.8 g/L for almond shells after steam explosion and 42 g/L for hydrothermally pretreated olive pruning residue.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-65977 (URN)10.1080/17597269.2017.1378988 (DOI)000456114000002 ()2-s2.0-85030181650 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-04-12 (johcin)

Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2019-04-12Bibliographically approved
Matsakas, L., Nitsos, C., Vörös, D., Rova, U. & Christakopoulos, P. (2017). High-Titer Methane from Organosolv-Pretreated Spruce and Birch. Energies, 10(3), Article ID 263.
Open this publication in new window or tab >>High-Titer Methane from Organosolv-Pretreated Spruce and Birch
Show others...
2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 3, article id 263Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
MDPI, 2017
Keywords
biogas, methane, lignocellulosic biomass, organosolv pretreatment, anaerobic digestion, birch, spruce
National Category
Bioenergy Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-62838 (URN)10.3390/en10030263 (DOI)000398736700003 ()2-s2.0-85017581416 (Scopus ID)
Funder
Bio4Energy
Note

Validerad; 2017; Nivå 2; 2017-04-03 (andbra)

Available from: 2017-04-01 Created: 2017-04-01 Last updated: 2019-09-12Bibliographically approved
Nitsos, C., Stoklosa, R. J., Karnaouri, A. C., Vörös, D., Lange, H., Hodge, D., . . . Christakopoulos, P. (2016). Isolation and Characterization of Organosolv and Alkaline Lignins from Hardwood and Softwood Biomass. ACS Sustainable Chemistry and Engineering, 4(10), 5181-5193
Open this publication in new window or tab >>Isolation and Characterization of Organosolv and Alkaline Lignins from Hardwood and Softwood Biomass
Show others...
2016 (English)In: ACS Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 4, no 10, p. 5181-5193Article in journal (Refereed) Published
Abstract [en]

Isolation of lignins from hardwood and softwood biomass samples, containing 26.1% and 28.1% lignin, respectively, has been performed with the use of alkaline and organosolv pretreatment methods. The effect of catalyst loading, ethanol content, particle size, and pretreatment time on the yields and properties of the isolated lignins were investigated. Alkaline lignins had higher carbohydrate content - up to 30% - and exhibited higher molecular weights in the range of 3000 Da, with a maximum phenolic hydroxyl content of 1 mmol g-1 for birch and 2 mmol g-1 for spruce. Organosolv lignins, on the other hand, showed high purity - 93% or higher - despite the more extensive biomass dissolution into the pretreatment medium; they also exhibited a lower range of molecular weights between 600 and 1600 Da depending on the source and pretreatment conditions. Due to the lower molecular weight, phenolic hydroxyl content was also increased, reaching as high as 4 mmol g-1 with a simultaneous decrease in aliphatic hydroxyl content as low as 0.6 mmol g-1. Efficient lignin dissolution of 62% for spruce and 69% for birch, achieved at optimal pretreatment conditions, was combined with extensive hemicellulose removal

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-60086 (URN)10.1021/acssuschemeng.6b01205 (DOI)000384791500009 ()2-s2.0-84989952894 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-11-01 (andbra)

Available from: 2016-11-02 Created: 2016-11-01 Last updated: 2018-07-10Bibliographically approved
Nitsos, C., Matsakas, L., Triantafyllidis, K., Rova, U. & Christakopoulos, P. (2015). Evaluation of Mediterranean Agricultural Residues as a Potential Feedstock for the Production of Biogas via Anaerobic Fermentation (ed.). BioMed Research International, 2015, Article ID 171635.
Open this publication in new window or tab >>Evaluation of Mediterranean Agricultural Residues as a Potential Feedstock for the Production of Biogas via Anaerobic Fermentation
Show others...
2015 (English)In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, Vol. 2015, article id 171635Article in journal (Refereed) Published
Abstract [en]

Hydrothermal, dilute acid, and steam explosion pretreatment methods, were evaluated for their efficiency to improve the methane production yield of three Mediterranean agricultural lignocellulosic residues such as olive tree pruning, grapevine pruning, and almond shells. Hydrothermal and dilute acid pretreatments provided low to moderate increase in the digestibility of the biomass samples, whereas steam explosion enabled the highest methane yields to be achieved for almond shells at 232.2 ± 13.0 mL CH4/gVS and olive pruning at 315.4 ± 0.0 mL CH4/gVS. Introduction of an enzymatic prehydrolysis step moderately improved methane yields for hydrothermal and dilute acid pretreated samples but not for the steam exploded ones.

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-14673 (URN)10.1155/2015/171635 (DOI)000364863200001 ()26609521 (PubMedID)2-s2.0-84947968804 (Scopus ID)e166e0ba-2003-4cdf-a3df-73db99a45191 (Local ID)e166e0ba-2003-4cdf-a3df-73db99a45191 (Archive number)e166e0ba-2003-4cdf-a3df-73db99a45191 (OAI)
Note

Validerad; 2015; Nivå 2; 20151104 (leomat)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Nitsos, C., Matis, K. A. & Triantafyllidis, K. (2013). Optimization of hydrothermal pretreatment of lignocellulosic biomass in the bioethanol production process (ed.). Paper presented at . ChemSusChem, 6(1), 110-122
Open this publication in new window or tab >>Optimization of hydrothermal pretreatment of lignocellulosic biomass in the bioethanol production process
2013 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 6, no 1, p. 110-122Article in journal (Refereed) Published
Abstract [en]

The natural resistance to enzymatic deconstruction exhibited by lignocellulosic materials has designated pretreatment as a key step in the biological conversion of biomass to ethanol. Hydrothermal pretreatment in pure water represents a challenging approach because it is a method with low operational costs and does not involve the use of organic solvents, difficult to handle chemicals, and "external" liquid or solid catalysts. In the present work, a systematic study has been performed to optimize the hydrothermal treatment of lignocellulosic biomass (beech wood) with the aim of maximizing the enzymatic digestibility of cellulose in the treated solids and obtaining a liquid side product that could also be utilized for the production of ethanol or valuable chemicals. Hydrothermal treatment experiments were conducted in a batch-mode, high-pressure reactor under autogeneous pressure at varying temperature (130-220 °C) and time (15-180 min) regimes, and at a liquid-to-solid ratio (LSR) of 15. The intensification of the process was expressed by the severity factor, log Ro. The major changes induced in the solid biomass were the dissolution/removal of hemicellulose to the process liquid and the partial removal and relocation of lignin on the external surface of biomass particles in the form of recondensed droplets. The above structural changes led to a 2.5-fold increase in surface area and total pore volume of the pretreated biomass solids. The enzymatic hydrolysis of cellulose to glucose increased from less than 7 wt % for the parent biomass to as high as 70 wt % for the treated solids. Maximum xylan recovery (60 wt %) in the hydrothermal process liquid was observed at about 80 wt % hemicellulose removal; this was accomplished by moderate treatment severities (log R o=3.8-4.1). At higher severities (log Ro=4.7), xylose degradation products, mainly furfural and formic acid, were the predominant chemicals formed. Green fuels and chemicals: The enzymatic digestibility of cellulose in lignocellulosic biomass towards fermentable glucose can be increased significantly by hydrothermal pretreatment in pure water under relatively mild conditions. Appropriate selection of the pretreatment temperature and time also leads to a process liquid that can be enriched in xylose or in furfural and acetic acid

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-4039 (URN)10.1002/cssc.201200546 (DOI)1e5989f6-b06e-4884-9e14-6e6efd466e59 (Local ID)1e5989f6-b06e-4884-9e14-6e6efd466e59 (Archive number)1e5989f6-b06e-4884-9e14-6e6efd466e59 (OAI)
Note
Upprättat; 2013; 20160225 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Nitsos, C., Mihailof, C. M., Matis, K. A., Lappas, A. A. & Triantafyllidis, K. (2013). The Role of Catalytic Pretreatment in Biomass Valorization Toward Fuels and Chemicals (ed.). In: (Ed.), (Ed.), The Role of Catalysis for the Sustainable Production of Bio-fuels and Bio-chemicals: (pp. 217-260). Paper presented at . : Elsevier
Open this publication in new window or tab >>The Role of Catalytic Pretreatment in Biomass Valorization Toward Fuels and Chemicals
Show others...
2013 (English)In: The Role of Catalysis for the Sustainable Production of Bio-fuels and Bio-chemicals, Elsevier, 2013, p. 217-260Chapter in book (Refereed)
Abstract [en]

The enzymatic hydrolysis of cellulose toward fermentable glucose is of paramount importance for the production of ethanol or other high-value chemicals from lignocellulosic biomass via the biochemical route. A pretreatment step is usually required that alters the structure and composition of biomass, reduces its recalcitrance, and allows the efficient enzymatic conversion of carbohydrates into sugars. Biomass pretreatment aims mainly at the selective separation of hemicellulose and/or lignin, either as oligomers or as smaller sugar and phenolic molecules, which can be further converted enzymatically or via chemical catalysis to platform chemicals or fuel precursors. In this chapter, a review of the most widely applied pretreatment methods is presented, with the aim of elucidating the role of chemical or biochemical catalysis in this first step of biomass valorization

Place, publisher, year, edition, pages
Elsevier, 2013
National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-21359 (URN)10.1016/B978-0-444-56330-9.00007-3 (DOI)dd0adc79-3611-42fb-8aff-2b5c55a34128 (Local ID)9780444563309 (ISBN)dd0adc79-3611-42fb-8aff-2b5c55a34128 (Archive number)dd0adc79-3611-42fb-8aff-2b5c55a34128 (OAI)
Note
Upprättat; 2013; 20160302 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Stephanidis, S., Nitsos, C., Kalogiannis, K. G., Iliopoulou, E. F., Lappas, A. A. & Triantafyllidis, K. (2011). Catalytic upgrading of lignocellulosic biomass pyrolysis vapours: Effect of hydrothermal pre-treatment of biomass (ed.). Paper presented at . Catalysis Today, 167(1), 37-45
Open this publication in new window or tab >>Catalytic upgrading of lignocellulosic biomass pyrolysis vapours: Effect of hydrothermal pre-treatment of biomass
Show others...
2011 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 167, no 1, p. 37-45Article in journal (Refereed) Published
Abstract [en]

The main objective of the present work was the study of the effect of hydrothermal pretreatment of lignocellulosic biomass (beech wood) on the product yields and bio-oil composition produced from biomass flash pyrolysis as well as from the catalytic upgrading of the biomass pyrolysis vapours. The hydrothermal pretreatment of lignocellulosic biomass was performed at a severity factor (Ro) of 3.55 leading to ∼35 wt.% loss of solids, mainly due to solubilization and removal of hemicellulose. The production of sugars (mainly levoglucosan) was significantly increased by the use of the hydrothermally pretreated biomass instead of the untreated biomass in the non-catalytic flash pyrolysis experiments. On the other hand, the concentration of carboxylic acids, ketones and phenols was decreased in the bio-oil derived from the pretreated biomass. The catalysts tested in the upgrading of the biomass pyrolysis vapours were the strongly acidic zeolites H-ZSM-5 and silicalite (with very low number of acid sites) and the mildly acidic mesoporous aluminosilicate Al-MCM-41. The effect of catalysts on product yields and composition of bio-oil in the upgrading of pyrolysis vapours, was similar for both the pretreated and untreated biomass. The use of zeolite H-ZSM-5 decreased the total liquid yield (bio-oil) via decreasing the organic phase of bio-oil and increasing its water content, accompanied by increase of gases and moderate formation of coke on the catalyst. The zeolite silicalite and the Al-MCM-41 induced similar effects with those of H-ZSM-5 but to a less extent, except of the significantly higher coke that was deposited on Al-MCM-41. With regard to the composition of the bio-oil, all the catalysts and mostly the strongly acidic H-ZSM-5 zeolite reduced the oxygen content of the organic fraction, mainly by decreasing the concentration of acids, ketones and phenols in the untreated biomass pyrolysis oil or the concentration of sugars in the pretreated biomass pyrolysis oil. Aromatics and polycyclic aromatic hydrocarbons (PAHs) were significantly increased by the use of all catalysts, for both types of biomass feed. A substantial increase in the concentration of phenols was observed in the upgraded bio-oil derived by the hydrothermally pretreated biomass, using the less acidic silicalite and Al-MCM-41 catalysts

National Category
Bioprocess Technology
Research subject
Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-10969 (URN)10.1016/j.cattod.2010.12.049 (DOI)9de152ca-302c-4b45-93e3-66a7e9c12f29 (Local ID)9de152ca-302c-4b45-93e3-66a7e9c12f29 (Archive number)9de152ca-302c-4b45-93e3-66a7e9c12f29 (OAI)
Note
Upprättat; 2011; 20160302 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9868-9031

Search in DiVA

Show all publications