Dilute sulfuric acid pretreatment of sunflower stalks for sugar production..pdf

Bioresource Technology 140 (2013) 292–298Contents lists available at SciVerse ScienceDirect Bioresource Technology journal homepage: www.elsevier .com/locate /bior techDilute sulfuric acid pretreatment of sunflower stalks for sugar production0960-8524/$ - see front matter  2013 Elsevier Ltd. All rights reserved. /10.1016/j.biortech.2013.04.104 ? Corresponding author. Tel.: +34 953212163; fax: +34 953212141. E-mail address: ecastro@ujaen.es (E. Castro).Encarnación Ruiz, Inmaculada Romero, Manuel Moya, Cristóbal Cara, Juan D. Vidal, Eulogio Castro ? Department of Chemical, Environmental and Materials Engineering, Agrifood Campus of International Excellence ceiA3, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain h i g h l i g h t s  Sunflower stalks are a potential feedstock for the production of bioethanol.  The effect on sugar production of pretreatment variables is assessed.  Pretreatment of 100 g sunflower stalks results in 33 g of glucose and xylose.  2/3 Of the initial sugars are available for fermentation after pretreatment.a r t i c l e i n f o Article history: Received 18 March 2013 Received in revised form 25 April 2013 Accepted 26 April 2013 Available online 6 May 2013 Keywords: Agricultural residues Dilute acid Pretreatment Enzymatic hydrolysis Sunflower stalksa b s t r a c t In this work the pretreatment of sunflower stalks by dilute sulfuric acid is studied. Pretreatment temper- ature and the concentration of acid solution were selected as operation variables and modified according to a central rotatable composite experimental design. Based on previous studies pretreatment time was kept constant (5 min) while the variation range for temperature and acid concentration was centered at 175 C and 1.25% (w/v) respectively. Following pretreatment the insoluble solids were separated by fil- tration and further submitted to enzymatic hydrolysis, while liquid fractions were analyzed for sugars and inhibitors. Response surface methodology was appl