Pretreatment of wheat straw using deep eutectic solvents and ultrasound

Transcription

1 Pretreatment of wheat straw using deep eutectic solvents and ultrasound Andrea Škulcová, Michal Jablonský, Aleš Ház, Milan Vrška Slovak University of Technology in Bratislava, Faculty of Chemical and Food Technology, Institute of natural and synthetic polymers, Department of wood, pulp and paper

2 INTRODUCTION new solvent systems are the great challenge in the field of green chemistry lignin GOAL biomass commercial technology - fragmentation/ isolation polysaccharides others 2

3 DEEP EUTECTIC SOLVENTS (DESs) generally mixture of two or more components with EUTECTIC POINT eutectic mixture hydrogen bonds (donors and acceptors) Fig 1: Formation of hydrogen bond between choline and oxalic acid preparation of DES temperature up to 100 C and atmospheric pressure 3

4 DEEP EUTECTIC SOLVENTS (DESs) Tab 1: Lignin removal from biomass using different DESs in [%] Substrate HBA DES HBD Molar ratio Decrease of lignin content by [%] Reference Wheat straw Lactic acid 1:2 1: Malic acid 1: Oxalic acid 1: De Dio (2013) Pine wood Lactic acid 1:2 1: Malic acid 1: Oxalic acid 1: De Dio (2013) Rice straw Lactic acid 2:1 5:1 9: Betaine 2:1 5: Kumar et al. (2015) Lactic acid 1:9 1: Wheat straw Malonic acid 1:1 3.8 Urea 1:2 1.3 Jablonský et al. (2015) Oxalic acid 1:

5 DEEP EUTECTIC SOLVENTS (DESs) Tab 1: Lignin removal from biomass using different DESs in [%] Substrate HBA DES HBD Molar ratio Decrease of lignin content by [%] Reference Wheat straw Pine wood Lactic acid 1:2 1: Malic acid 1: Oxalic acid 1: Lactic acid 1:2 1: Malic acid 1: Oxalic acid 1: De Dio (2013) De Dio (2013) 14 h 60 C Rice straw Lactic acid 2:1 5:1 9: Betaine 2:1 5: Kumar et al. (2015) 12 h 60 C Lactic acid 1:9 1: Wheat straw Malonic acid 1:1 3.8 Urea 1:2 1.3 Oxalic acid 1: Jablonský et al. (2015) 24 h 60 C 5

6 ULTRASOUND IN BIOMASS PRETREATMENT modification of cell wall fibre is more flexible swelling better binding capacity fibrillation of fibre better tensile strength sonotrode BETTER PENETRATION generator suspension Fig 2: Ultrasonic impregnation 6

7 EXPERIMENT DELIGNIFICATION WITHOUT ULTRASOUND grinded wheat straw (600 mesh) laboratory experiment DES lactic acid: choline (9:1, 10:1) oxalic acid: choline (1:1) malonic acid: choline (1:1) urea: choline (2:1) delignification time 24 h reaction temperature 60 C Fig 4: Prepared DES (lactic acid: choline, oxalic acid: choline, malonic acid: choline, urea: choline ) Fig 3: Grinded wheat straw 7

8 EXPERIMENT DELIGNIFICATION WITHOUT ULTRASOUND Total lignin content in grinded wheat straw was 17.3 % Deep eutectic solvent Lactic acid Molar ratio 1: : Malonic acid 1:1 3.8 Urea 1:2 1.3 Oxalic acid 1: Amount of removed lignin from total lignin [%] Fine extracted straw Cellulose Hemicelluloses Lignin Ash 8

9 EXPERIMENT DELIGNIFICATION WITHOUT ULTRASOUND cut wheat straw (2 5 cm) DES lactic acid: choline (10:1) delignification time 5, 10, 20, 30, 50, 70 h 60 C DELIGNIFICATION WITH ULTRASOUND cut wheat straw (2-5 cm) DES lactic acid: choline (10:1) delignification time 5, 10, 20, 30, 50, 70 h 60 C ultrasound 5 min Fig 5: Prepared wheat straw and DES (lactic acid: choline ) 9

10 EXPERIMENT DELIGNIFICATION WITHOUT ULTRASOUND DELIGNIFICATION WITH ULTRASOUND Total lignin content in cut wheat straw is 17.0 % Reaction time [h] Amount of removed lignin from total lignin [%] Cellulose Hemicelluloses Lignin Extractives Ash Reaction time [h] Amount of removed lignin from total lignin [%] without US with 5 min US

11 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 ACKNOWLEDGEMENTS 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 , and the project of National Centre for Research and Application of Renewable Energy Sources, ITMS: , and the project Finalization of Infrastructure of the National Centre for Research and Application of Renewable Energy Sources, ITMS: , and the project Competence centre for new materials, advanced technologies and energetics ITMS: , co-funded by the European Regional Development Fund. This publication was supported by the Slovak Research and Development Agency under the contract No. APVV , APVV , VEGA 1/0775/13 and project Bark Extra: Study of obtaining extractive compounds and their use (Grant STU for young scientist). 11

12 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 12