Comparison of pulp species in IONCELL-P: selective hemicellulose extraction method with ionic liquids

Abstract

In our recent studies, it was demonstrated that the IONCELL-P process selectively dissolves hemicelluloses from bleached birch kraft pulp in a mixture of 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) and water as a solvent system. The IONCELL-P method refines papergrade pulp to dissolving pulp with < 5% hemicelluloses and allows isolation of polymeric xylan without yield losses or polymer degradation. This paper is a comparative study where paper-grade pine, birch, and eucalyptus pulps are subjected to the IONCELL-P process with two [emim]-based ionic liquids (ILs), i.e. [emim]acetate and [emim]dimethylphosphate. Also, the effect of an endoglucanase pretreatment was investigated to check whether 1) the pulp viscosity could be adjusted for the following process steps before the hemicellulose extraction and 2) the decreasing pulp viscosity would open the fiber structure and thus enhance the extraction. Under optimum conditions, the birch xylan content could be reduced from 25.4% down to 1.3% and for eucalyptus from 16.6% to 2.4%. Pine pulp xylan and glucomannan were decreased from 8.1% and 7.1% to 0.9% and 2.2%, respectively. The residual hemicellulose contents of the pine pulp could be further decreased with a hemicellulase pretreatment. The selectivity of the dissolution towards hemicelluloses was better for hardwoods. Adjusting the pulp viscosity by endoglucanase prior to the IONCELL-P process reduced the selectivity as short-chain cellulose molecules were extracted along with the hemicelluloses.

Purification of Kraft cellulose under mild conditions using choline acetate based deep eutectic solvents

“…36,37 Nevertheless, all the industrial applications of lignocellulosic biomasses pretreatment based on ILs suffer from the high costs of ILs, thus posing limitations for large-scale development of ILsbased processes. [38][39][40][41] Additionally, toxicity and long-term recyclability can also represent severe issues.…”

Cellulose Nanofibril (CNF) Films and Xylan from Hot Water Extracted Birch Kraft Pulps

“…Their utilization potential comes mainly determined by the purity, molar mass and degree of substitution. In recent years, several strategies to recover the hemicelluloses from pulp have been investigated using alkali [25,26], ionic liquids [27], and hydrothermal treatments [28,29]. Among those, the hydrothermal treatment offers the obvious advantage of being an environmentally friendly process, as water is the only solvent used.…”

Supported Ionic Liquid Membranes for Separation of Lignin Aqueous Solutions

“…The physicochemical properties can be customized by an optimal combination of the most convenient cations and anions for each application. The viability of ILs for dissolution, separation, and recovery of the main components of lignocellulosic biomass has been investigated [34][35][36][37][38][39][40][41][42]. Imidazolium based ILs (with different radicals joined to the central ring and combined with simple inorganic and more complex organic anions) have been deeply investigated for the selective dissolution of lignin, since they are not good solvents for cellulose or hemicellulose [43][44][45].…”