Industrial Crops and Products 55 (2014) 109–115 Contents lists available at ScienceDirect Industrial Crops and Products jo ur nal home p age: www.elsevier.com/locate/indcrop Enhanced mass transfer upon switchable ionic liquid mediated wood fractionation Valerie Eta a,∗ , Ikenna Anugwom a , Pasi Virtanen a , P. Mäki-Arvela a , J.-P. Mikkola a,b a Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku FI-20500, Finland b Technical Chemistry, Department of Chemistry, Chemical-Biological Center, Umeå University, SE-901 87 Umeå, Sweden a r t i c l e i n f o Article history: Received 10 October 2013 Received in revised form 10 January 2014 Accepted 2 February 2014 Available online 7 March 2014 Keywords: SpinChem device Switchable ionic liquids Birch chips Fractionation DBU Power draw a b s t r a c t The fractionation of lignocellulosic biomass to its major components is the primary step towards the conversion of biomass-based biopolymers to commodity chemicals in the integrated biorefinery process. Wood chips encased in a SpinChem ® device and attached to the stirrer of a batch autoclave were used together with switchable ionic liquids (SILs) for the selective fractionation of hemicelluloses and lignin. Stirring of the wood chips in the SpinChem ® device facilitated the diffusion of SIL into the chips through forced recirculation and at the same time avoiding mechanical fibrillation. The treatment of birch chips (Betula pendula) with SILs comprising 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU), monoethanolamine (MEA) and CO2 at 120 ◦ C in a SpinChem ® device resulted in the fractionation of 82 wt.% hemicelluloses and 90 wt.% lignin, leaving the cellulose-rich non-dissolved material partially fibrillated and softened. The dissolved hemicelluloses and lignin were selectively precipitated using isopropanol and recovered from the spent SIL. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Biomass constitutes an abundant and widely available source for bio-energy supplying about 10% of the current global primary energy. Through thermochemical and biochemical technologies lignocellulosic biomass may be converted to energy (heat, fuels), energy carriers (charcoal, torrefied ‘bio-coal’, bio-oil) and plat- form chemicals (Binder and Raines, 2009; Shishir et al., 2011; Klass, 2004; Taarning et al., 2011), allowing for the displacement and/or replacement of diminishing fossil fuels with carbon neu- tral resources. The composite micro-structure of lignocellulosic biomass consists mainly of cellulose, hemicellulose and lignin, with minor quantities of extractives and inorganic matter. The irregular and highly condensed cross-linked network of lignin cements hemicelluloses and cellulose together and also forms lignin–carbohydrate complexes in plant cell walls, thus, providing the lignocellulosic material with structural rigidity to resist exter- nal stress (Jing-Ke Weng and Clint Chapple, 2010). These complex chemical and structural mechanisms contribute to the superb resis- tance of the plant tissue against invasion of the living cells by fungi and other microorganisms in the living plant but also constitute the structural recalcitrance of biomass towards fractionation (Himmel et al., 2007). ∗ Corresponding author. Tel.: +358 408769993. E-mail address: valerie.eta@abo.fi (V. Eta). Pretreatment of lignocellulosic biomass disrupts the complex polymer matrix of lignocellulosic materials via the cleavage of hydrogen, ether, ester and carbon-oxygen bonds thereby improv- ing accessibility of enzymes or chemicals during processing. Steam explosion, carbon dioxide explosion, hot water treatment, dilute acid treatment, alkali treatment organosolv processes, ammonia treatment and ozonolysis have been proposed as pretreatment methods for lignocellulosic biomass through the breakdown of intra- and intermolecular hydrogen bonds and disassembling the crystalline lattice of cellulose (Kumar et al., 2009). However, extreme conditions such as, high temperature and pressure, use of acids or bases may result in sugar degradation, enzyme-inhibition products or necessitate special equipment. The release of pollut- ants, salts from acid/base neutralization and solvent consumption have prompted the search for efficient, recyclable pretreatment alternatives such as, ionic liquids. Ionic liquids have recently attracted attention for the dissolu- tion of cellulose, lignin and other non-wood products by facilitating partial or complete disassembly of the crystalline lattice of native cellulose and the deconstruction of the polymer network of lignin (Swatloski et al., 2002; Zhao et al., 2009; Li et al., 2010). Cellu- lose dissolution has been achieved using ionic liquids based on a multitude of designs though the use of acetate or phosphonate anions is favoured due to their contribution to low viscosity, hydro- gen bond interaction and their interaction with cations (Liu et al., 2010). The extraction of lignin has also been demonstrated using 1- ethyl-3-methyl imidazolium xylene sulfonate at 170–190 ◦ C while 0926-6690/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2014.02.001