Use of residues from renewable biomass for technological applications: Sawdust from Pinus elliottii as source of xylans

OCHOA TORRES, DENISSE SOFÍA; FERNÁNDEZ, PAULA VIRGINIA; CIANCIA, MARINA; ERREA, MARÍA INÉS

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

Asociación Argentina de Ingenieros Químicos

Pinus elliottii (slash pine), is a conifer tree (softwood) commercially cultivated in north-eastern region of Argentina. Its wood is known for an un usually high strength, and very fast growth, that makes it very suitable as raw material to produce sawn timber for construction. However, around 56% of this wood generates a residue1, which is only partially reutilized. In a first stage of a work that aims to use sawdust as renewable biomass for technological application, thepolysaccharides of this residue were extracted, and their structures were studied.Finely milled sawdust (particle size, 105-420 um) was extracted sequentially with ethanol and ammonium oxalate aqueous solution, to eliminated low molecular weight components and pectins, respectively. To avoid degradation of the polysaccharides, the residue was suspended in water and reduced with NaBH4 overnight. Then, KOH was added to give a 4M KOH solution, which was heated in argon atmosphere for 1h under reflux. The mixture was brought to room temperature, neutralized, dialyzed (MW cut off 6-8,000), and lyophilized. This procedure was repeated three times,obtaining extracts PE1, PE2, and PE3, and a final residue, RF. Neutral carbohydrate and uronic acid content were determined spectrophotometrically. Monosaccharides composition of the extracts was determined by GLC-mass spectrometry of their alditol acetates. Structural analyses were completed by NMR spectroscopy.Extracts (PE1-PE3) were constituted by major amounts of xylose and uronic acids. In the anomeric region of the HSQC NMR spectrum only signals corresponding to 4-linked β-D-xylopyranose units (102.5/4.46 and 102.2/4.62 ppm) and α - D-glucuronic acid (98.6/5.27 ppm) were significant. These results indicate that the predominant polysaccharides of the extracts were 4-linked β-D-xylans, partially substituted by α -D-glucuronic acid at position 2 (Figure 1).