Valorization of Paulownia tomentosa wood wastes to produce cellulose nanocrystals

Background: Paulownia tomentosa wood has chemical properties that satisfy the requirements for good raw material to obtain cellulose-based products, such as nanocellulose. Cellulose nanocrystals (CNC) are derived from naturally occurring cellulosic fibers, constituted of cellulose chains with an organizational setting that results in rigid rod-shaped crystals. This study assessed the wood wastes from Paulownia tomentosa Steud. as raw material for producing cellulose nanocrystals (CNC) using alkaline and delignification treatments, followed by a hydrolysis process with sulfuric acid at the 52% and 58% concentrations. The isolation of CNC from Paulownia tomentosa wood wastes was confirmed through different spectroscopic analyses. Results: The suspensions of nanocrystalline cellulose CNC-52 and CNC-58 showed yields of 8.34% and 7.62%, respectively. The particle size distribution of the suspensions, determined by the AFM technique, presented an average of L = 180.01 nm and W = 20.46 nm in CNC-52 and L = 128.06 nm and W = 10.18 nm in CNC-58. Moreover, the FTIR and XRD results demonstrated that there was no difference in the structure of the crystalline network and the chemical composition between cellulose (Kiri-CB) and the CNC. Conclusion: The results obtained from this study allowed to conclude that it is possible to employ the Paulownia tomentosa wood waste as a source of cellulose for extracting CNC by hydrolysis, adjusting the sulfuric acid concentration to 58% and maintaining it at 45 degrees C for 60 min.