Journal of Biotechnology 162 (2012) 415–421 Contents lists available at SciVerse ScienceDirect Journal of Biotechnology jou rn al hom epage: www.elsevier.com/locate/jbiotec Fractionation of sulphite spent liquor for biochemical processing using ion exchange resins D.L.A. Fernandes, C.M. Silva, A.M.R.B. Xavier, D.V. Evtuguin ∗ CICECO, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal a r t i c l e i n f o Article history: Received 4 January 2012 Received in revised form 9 March 2012 Accepted 15 March 2012 Available online 23 March 2012 Keywords: Sulphite spent liquor Lignosulphonates Sugars Fermentation Ion exchange resin Bioethanol a b s t r a c t Sulphite spent liquor (SSL) is a side product from acidic sulphite pulping of wood, which organic coun- terpart is composed mainly by lignosulphonates (LS) and sugars. The last are a prominent substrate for the bioprocessing although a previous purification step is necessary to eliminate microbial inhibitors. In this study a fractionation of hardwood SSL (HSSL) has been accomplished employing ion exchange resins in order to separate sugars fraction from concomitant inhibitors: LS, acetic acid, furan derivatives, phenolics, acetic acid and excess of inorganic salts. The fractionation of HSSL has been carried out using two fixed-bed ion exchangers in series (cationic + anionic). The first cation exchange column packed with Dowex 50WX2 resin was able to eliminate free cations and partially separate sugars from high molecu- lar weight LS and furan derivatives. The second anion exchange column packed with Amberlite IRA-96 sorbed remaining LS, phenolics and acetic acid. Overall, the series arrangement under investigation has removed 99.99% of Mg 2+ , 99.0% of Ca 2+ , 99.6% of LS, and 100% of acetic acid, whereas the yield of recovered sugars was at least 72% of their total amount in HSSL. © 2012 Elsevier B.V. All rights reserved. 1. Introduction The world is facing a reduction of global fossil fuels resources, while energy requirements are progressively growing up. Alter- natives to produce fuel and chemicals from non-fossil feedstocks are attracting considerable interest around the world, in order to answer such needs and minimizing environmental impacts (Alvarado-Morales et al., 2009; Brehmer et al., 2009; Gonzalez- Garcia et al., 2009; Mussatto et al., 2010; Sannigrahi et al., 2010). Bioethanol is an attractive biofuel, since it can be easily pro- duced in large scale for blending with gasoline or to be used as pure “green” fuel. Bioethanol can be generated from different renewable raw materials containing simple sugars, starch or more complex substrates as lignocellulose (Balat, 2011; Balat et al., 2008; Chen and Qiu, 2010; Gonzalez-Garcia et al., 2009; Mussatto et al., 2010). In last years, numerous studies has been focused towards biotechnological strategies for the production of the so called “sec- ond generation” biofuels, utilizing, for instance, forestry wastes (Balat, 2011; Chen and Qiu, 2010), residual agricultural biomass (Huang et al., 2009; Nigam, 2001b; Zanichelli et al., 2007), and industrial wastes (Guimarães et al., 2010; Xavier et al., 2010). This kind of materials avoid social disturbance, since do not compete with food crops causing the rise of food prices such as sucrose ∗ Corresponding author. Tel.: +351 234 401 526; fax: +351 234 380084. E-mail address: Dmitrye@ua.pt (D.V. Evtuguin). or grains used for the “first generation” bioethanol fermentation (Alvarado-Morales et al., 2009; Bacovsky et al., 2010; Xavier et al., 2010). The production of bioethanol from non-food staff is an emerging challenge in the area. Sulphite spent liquors (SSLs) are side prod- ucts from acidic sulphite pulping of wood, and are normally burned to recover energy and the inorganic base (Casey, 1980; Fernandes et al., 2012). SSLs are produced in large amounts, about 90 billion litres annually worldwide (Lawford and Rousseau, 1993). In partic- ular, approximately 1 million tons of bleached sulphite eucalyptus pulp is produced per year, and 8–10 m 3 of hardwood sulphite spent liquors (HSSL) are produced per ton of pulp (Lawford and Rousseau, 1993; Marques et al., 2009a). The major components of SSLs are lignosulphonates (LS) and sugars, which are recognized valuable by-products for the produc- tion of added value products (Hocking, 1997; Plank, 2004; Goheen, 1971). With regard to bioethanol, SSL exhibits advantages over common lignocellulosic materials, because during the wood pulp- ing step a series of monomeric sugars are released, thus avoiding complex industrial hydrolysis processes (Fernandes et al., 2012). However, SSL contains several low- and high-molecular weight fer- mentation inhibitors, namely LS, acetic acid, phenolics and high levels of cationic species, that require a previous detoxification step (Xavier et al., 2010). Hence, the separation and purification of the sugars fraction of HSSL are needed to provide an adequate substrate stream for bioconversion into ethanol. Ion exchange chromatogra- phy is frequently used as a separation tool in bioprocessing (Cramer and Holstein, 2011). 0168-1656/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jbiotec.2012.03.013