HEMICELLULOSES EXTRACTION FROM PINE SAWDUST: A KINETIC STUDY OF SPENT LIQUOR RE-USE

CLAUSER, N.M.; FELISSIA, F.E.; AREA, M.C.; VALLEJOS, M.E.; GUTIÉRREZ, S.

São Paulo

Congreso; ABTCP - CIADICYP 2018 51º ABTCP Congresso Internacional de Celulose e Papel e X Congresso Ibero-Americano de Pesquisa em Celulose e Papel; 2018

ABTCP - CIADICYP

Pine sawdust is animportant lignocellulosic waste from the primary industrialization of wood inArgentina and Uruguay, so its valorization using the biorefinery platform couldadd new value chains into its forest industry. Hemicelluloses fromlignocellulosic waste is abundant polymer with enormous potential forindustrial applications. The chemical structure of the hemicelluloses allowstheir use as precursors for a wide range of chemicals such as alcohols, organicacids, and furanic compounds. In a biorefinery context, pine sawdust can beseparated in a valuable cellulose solid fraction and the spent liquor. However,current alternatives for the valorization of hemicelluloses are commerciallylimited due to their high cost production. The spent liquor reuse for biomassdeconstruction could be a promising strategy to reduce water usage in thesystem and capital and operating costs. However, it is necessary to performexperiments in order to evaluate how a concentrated extraction media can affectthe hydrolysis process. The aim of this study was to analyze the re-use of thespent liquor in dilute acid pre-treatment for the hemicellulosic extraction andto determine a kinetic model of hexoses and pentoses solubilisation. Alkalipretreated pine sawdust was treated by dilute acid treatments to extract hemicelluloses(7.5 g/L H2SO4 at 150°C for 30 min and liquid to solidratio 10:1). The spent liquor was re-used four times, in order to determine thevariation in the sugar concentrations and their degradation compounds. The spent liquorcomposition from the diluted acid treatment was determined by HPLC. Asimplified first order kinetic model for sugar release and decomposition wasproposed. Using the experimental data of a diluted acid hydrolysis with freshwater, kinetic constants were obtained by parameter adjustment using maximumlikelihood estimation method. The model was used to predict the sugar anddegradation products of re-cycled experiments. Comparison between modelled andexperimental data allows to say that the model suitably describes sugarsolubilisation and decomposition. In order to consider the potentialbenefits of the re-usestrategy,overall costs has to be analyzed ina biorefinery context including the resulting cellulose quality. However, theresults obtained in this work allow to say that more than two recyclesshould not be suitable forpentoses or its derived valuable chemicals, as pentoses are strongly degraded.It could be useful for glucose- derived chemicals, and furfural or its derived chemicals.