pretreatment of wheat straw using deep eutectic solvents and ultraound
TRANSCRIPT
Pretreatment of wheat straw using deep eutectic solvents and
ultrasound
Andrea Škulcová, MSc.
Slovak University of Technology in Bratislava, Faculty of Chemical and Food Technology,
Institute of natural and synthetic polymers, Department of wood, pulp and paper
INTRODUCTION
• new solvent systems are the great challenge in the field of green chemistry
GOAL
commercial technology - fragmentation/ isolation
biomass
lignin
others polysaccharides
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DEEP EUTECTIC SOLVENTS (DESs)
• generally – mixture of two or more components with EUTECTIC POINT
• eutectic mixture – hydrogen bonds (donors and acceptors)
• preparation of DES – temperature up to 100°C and atmospheric pressure
Fig 1: Formation of hydrogen bond between choline chloride and oxalic acid
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DEEP EUTECTIC SOLVENTS (DESs)
Tab 1: Lignin removal from biomass using different DESs in [%]
Substrate DES
Molar ratio Decrease of lignin
content by [%] Reference
HBA HBD
Wheat straw Choline chloride
Lactic acid 1:2 1:9 3.95 7.89
De Dio (2013) Malic acid 1:1 2.89
Oxalic acid 1:1 18.68
Pine wood Choline chloride
Lactic acid 1:2 1:9 4.86 9.71
De Dio (2013) Malic acid 1:1 1.71
Oxalic acid 1:1 9.71
Rice straw Lactic acid Choline chloride 2:1 5:1 9:1 64.0 75.7 74.2
Kumar et al. (2015) Betaine 2:1 5:1 65.6 70.4
Wheat straw Choline chloride
Lactic acid 1:9 1:10 14.6 29.1
Jablonský et al. (2015)
Malonic acid 1:1 3.8
Urea 1:2 1.3
Oxalic acid 1:1 57.9
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DEEP EUTECTIC SOLVENTS (DESs)
Tab 1: Lignin removal from biomass using different DESs in [%]
Substrate DES
Molar ratio Decrease of lignin
content by [%] Reference
HBA HBD
Wheat straw Choline chloride
Lactic acid 1:2 1:9 3.95 7.89
De Dio (2013) Malic acid 1:1 2.89
Oxalic acid 1:1 18.68
Pine wood Choline chloride
Lactic acid 1:2 1:9 4.86 9.71
De Dio (2013) Malic acid 1:1 1.71
Oxalic acid 1:1 9.71
Rice straw Lactic acid Choline chloride 2:1 5:1 9:1 64.0 75.7 74.2
Kumar et al. (2015) Betaine 2:1 5:1 65.6 70.4
Wheat straw Choline chloride
Lactic acid 1:9 1:10 14.6 29.1
Jablonský et al. (2015)
Malonic acid 1:1 3.8
Urea 1:2 1.3
Oxalic acid 1:1 57.9
14 h 60 °C
12 h 60 °C
24 h 60 °C
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ULTRASOUND IN BIOMASS PRETREATMENT
• modification of cell wall fibre is more flexible
• swelling better binding capacity
• fibrillation of fibre better tensile strength
Fig 2: Ultrasonic impregnation
sonotrode
suspension generator
BETTER PENETRATION
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EXPERIMENT
DELIGNIFICATION WITHOUT ULTRASOUND
• grinded wheat straw (600 mesh) laboratory experiment
• DES lactic acid: choline chloride (9:1, 10:1)
oxalic acid: choline chloride (1:1)
malonic acid: choline chloride (1:1)
urea: choline chloride (2:1)
• delignification time 24 h
• reaction temperature 60 °C
Fig 4: Prepared DES (lactic acid: choline chloride, oxalic acid: choline chloride, malonic acid: choline chloride, urea: choline chloride)
Fig 3: Grinded wheat straw 7
EXPERIMENT
DELIGNIFICATION WITHOUT ULTRASOUND
Total lignin content in grinded wheat straw was 17.3 %
Deep eutectic solvent Molar ratio
Amount of removed lignin
from total lignin [%]
Choline chloride
Lactic acid 1:9 14.6
1:10 29.1
Malonic acid 1:1 3.8
Urea 1:2 1.3
Oxalic acid 1:1 57.9
Fine extracted straw
Cellulose Hemicelluloses Lignin Ash
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DELIGNIFICATION WITH ULTRASOUND
• cut wheat straw (2 - 5 cm)
• DES lactic acid: choline chloride (10:1) • delignification time 5, 10, 20, 30, 50, 70 h • 60 °C • ultrasound 5 min
EXPERIMENT
DELIGNIFICATION WITHOUT ULTRASOUND
• cut wheat straw (2 – 5 cm)
• DES lactic acid: choline chloride (10:1)
• delignification time 5, 10, 20, 30, 50, 70 h
• 60 °C
Fig 5: Prepared wheat straw and DES (lactic acid: choline chloride)
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DELIGNIFICATION WITH ULTRASOUND
EXPERIMENT
DELIGNIFICATION WITHOUT ULTRASOUND
Total lignin content in cut wheat straw is 17.0 %
Reaction time [h]
Amount of removed lignin
from total lignin [%]
5 14.3
10 18.9
20 21.7
30 29.2
50 34.7
70 46.7
Reaction time [h]
Amount of removed lignin
from total lignin [%]
5 15.1
10 22.3
20 24.5
30 34.2
50 41.6
70 51.1
Cellulose Hemicelluloses Lignin Extractives Ash
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without US with 5 min US
CONCLUSIONS
• DESs represent promising alternative solvent systems for biomass treatment
• ultrasonic treatment increases effect of impregnation by DES
• objective properties of used DESs bring high potential in process of lignocellulosics materials fractionation
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This article was created with the support of the Ministry of Education, Science, Research and Sport of the Slovak Republic within the Research and Development Operational Programme for the project "University Science Park of STU Bratislava", ITMS 26240220084, and the project of National Centre for Research and Application of Renewable Energy Sources, ITMS: 26240120016, and the project Finalization of Infrastructure of the National Centre for Research and Application of Renewable Energy Sources, ITMS: 26240120028, and the project Competence centre for new materials, advanced technologies and energetics ITMS: 26240220073, co-funded by the European Regional Development Fund. This publication was supported by the Slovak Research and Development Agency under the contract No. APVV-0850-11, APVV-14-0393, VEGA 1/0775/13 and project Bark Extra: Study of obtaining extractive compounds and their use (Grant STU for young scientist).
ACKNOWLEDGEMENTS
Andrea Škulcová, MSc. [email protected] Slovak University of Technology in Bratislava
Faculty of Chemical and Food Technology
Institute of natural and synthetic polymers Department of wood, pulp and paper
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