Bioprodutos obtidos da madeira de Paulownia tomentosa Steud.

Abstract

The motivation for the study of Paulownia tomentosa Steud., with the common name kiri, as the object of this thesis, was due to the limited knowledge of the forest sector, especially from the Brazilian scientific community, regarding this species with high productive potential, in addition to the possibilities development of high added value products. This work had as objective the valorization of the wood of Paulownia tomentosa Steud., through its physical and chemical characterization, and efficiency in obtaining bioproducts. Specifically, the objective was to point out the energy potential of kiri wood through carbonization, torrefaction and briquetting processes; and evaluate the use of wood sawdust for the production of cellulose nanocrystals by acid hydrolysis. Five trees of Paulownia tomentosa with 13 years old, discs were removed at proportional heights, from which the material was obtained for the characterization processes and bioproduct manufacturing. The basic density of Paulownia tomentosa wood was 0.269 g/cm³, and the percentage of wood chemical composition was 17.3% for total extractives, 17.1% for klason lignin (with S/G ratio of 1.15) and 67.7% for holocellulose (62.1% alpha-cellulose). Proximate chemichal composition indicated 86.5% volatile materials, 12.9% fixed carbon and 0.6% ash. The energy density was 1.28 Gcal/m³ and the IVC = 283. The total phenolic content of the ethanolic wood extract was 60.35 mg of AGE/100 g of extract, and the EC50 value was 0 .24 mg/mL. The carbonization of Paulownia tomentosa wood provided an increase of 19.5% in the energy density of biomass and for the fixed carbon yield and energetic yield, of 25.6% and 55.3%, respectively. The sawdust torrefaction at 250 ºC considerably increased the fixed carbon content by 31.5%, the energy density by 2.3% and the higher calorific value by 280.3 kcal/kg. The densification of biomass through the confection of briquettes provided positive effects in relation to energy density, even for the material that was not torrefied. The isolation of cellulose nanocrystalls (CNC) from Paulownia tomentosa wood, with high colloidal stability, was confirmed through different analyses. The torrefied briquettes and cellulose nanocrystalls, produced from sawdust, are also highlighted in the environmental issue, adding value to the species and contributing to the circular economy.