The effect of different pre-treatments to improve delignification of eucalypt stumps in a biorefinery context

Abstract

E. globulus stumps are recently considered as feedstock for pulp industries. Pre-treatments may improve delignification, increase pulp quality and promote other cellulosic applications. Five environmentally friendly pre-treatments were studied: liquid hot water (LHW), oxalic acid (OA), alkaline peroxide (AHP), sodium xylenesulfonate (SXS) and iron (III) chloride (FeCl3). The pre-treatments presented different yields: 94.7% (LHW), 92.7% (OA), 79.0% (AHP), 74.8% (SXS) and 78.9% (FeCl3). The chemical composition and FTIR analysis, including infrared structural ratios, of the pre-treated solids showed changes in cell wall structure. OA, SXS and FeCl3 pre-treatments were more selective for hemicelluloses extraction. Mass loss and pulp yield occurred considerably with AHP (21.0%; 53.9%), SXS (25.2%; 46.0%) and FeCl3 (21.1%; 30.7%). The pre-treated material was delignified by the kraft process, bleached using an ECF sequence (D0E1D1E2D2), and the pulp properties were evaluated. LHW improved the pulp physical properties while OA, AHP and SXS showed potential for production of dissolving pulps.