High-grade sulfur-free cellulose fibers by pre-hydrolysis and ethanol-alkali delignification of giant reed (Arundo donax L.) stems

Following to complex fractionation (biorefinery) scheme, the high-grade (purity) sulfur-free cellulosic pulps were produced from giant reed stems after selective removal of hemicelluloses by dilute sulfuric acid hydrolysis. Response surface methodology (RSM) was employed for statistical modeling and optimization of organosolv ethanol-alkali delignification using 2(4) central composite rotatable design (CCRD). The main process factors (effects and their interactions) affecting degree of pulp delignification and brightening were established and quantified. Analysis of variance (ANOVA) identified the effects of alkali concentration (linear and quadratic) as the more significant (p = 0). The optimum set of reaction conditions was defined by multiple regression analysis of the second-order polynomial model. Pulps with 4.3 Kappa number, 58.3% ISO brightness and 93.2% alpha-cellulose were produced under optimized conditions. (C) 2012 Elsevier B.V. All rights reserved.