Separation of Hemicellulose and Cellulose from Wood Pulp by Means of Ionic Liquid/Cosolvent Systems

Abstract

Pulp of high cellulose content, also known as dissolving pulp, is needed for many purposes, including the production of cellulosic fibers and films. Paper-grade pulp, which is rich in hemicellulose, could be a cheap source but must be refined. Hitherto, hemicellulose extraction procedures suffered from a loss of cellulose and the non-recoverability of unaltered hemicelluloses. Herein, an environmentally benign fractionation concept is presented, using mixtures of a cosolvent (water, ethanol, or acetone) and the cellulose dissolving ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIM OAc). This cosolvent addition was monitored using Kamlet-Taft parameters, and appropriate stirring conditions (3 h at 60 °C) were maintained. This allowed the fractionation of a paper-grade kraft pulp into a separated cellulose and a regenerated hemicellulose fraction. Both of these exhibited high levels of purity, without any yield losses or depolymerization. Thus, this process represents an ecologically and economically efficient alternative in producing dissolving pulp of highest purity.

Hot water treatment of hardwood kraft pulp produces high-purity cellulose and polymeric xylan

“…Several methods have been studied to remove the hemicelluloses from paper pulps, including enzymatic hydrolysis and cold caustic extraction (Gehmayr et al 2011;Ibarra et al 2009;Köpcke et al 2008), nitren extraction (Janzon et al 2006(Janzon et al , 2008, and ionic liquid extraction (Froschauer et al 2013;Roselli et al 2014). Despite their varying success in producing a high-purity pulp for dissolving applications, their high operational costs and/or their toxicity have limited the utilization of these methods in industrial scale.…”

Effect of methylimidazole on cellulose/ionic liquid solutions and regenerated material therefrom

“…Some of the most common cations are imidazolium, pyridinium, ammonium, and phosphonium derivatives [16]. Although imidazolium-based ILs are known to form covalent bonds with cellulose in some cases [17,18], they are still among the most used in academic research on ILs and cellulose and still highly interesting for biomass processing [19].…”

Hemicellulose-Based Hydrogels Present Status and Application Prospects: A Brief Review

“…There are several methods applied to separate the hemicellulose from the wood materials such as acid pretreatments (Nguyen, Tucker, Keller, & Eddy, 2000), alkaline extraction (Egüés, Sanchez, Mondragon, & Labidi, 2012), liquid hot-water extraction (Hasegawa, Tabata, Okuma, & Mae, 2004), steam treatment (Palm & Zacchi, 2003), ionic liquid extraction (Froschauer et al, 2013) and so on. These methods are available to extract the hemicellulose.…”