Valorization of sawdust biomass for biopolymer extraction via green method: Comparison with conventional process

Abstract

Summary The valorization of sawdust (SW) biomass by‐product, to extract cellulose through alkali and bleaching processes, including side‐streams to recover hemicellulose and lignin, is performed with the intention of evaluating differences with a proposed green method (GM). The study is developed with the intention of having a process at laboratory scale without leading to the complicated nanoscale processing. This study contemplates a process with scalable characteristics for the future, which contributes to wood processing waste around the world. Particularly, agroindustrial wastes from Durango (SWT1) and Hidalgo (SWT2), local communities of Mexico, were studied. SWT1 and SWT2 samples were processed with ethanol, sodium hydroxide followed by bleaching with sodium chlorite/acetic acid to remove, extractives (E), hemicellulose (H) and lignin (L), respectively. Selected‐SWT2 was processed through a proposed GM using hydrogen peroxide/sodium hydroxide. On the basis of results including Fourier transform infrared spectroscopy, thermogravimetric/differential analysis (TGA/DTG), X‐ray diffraction (XRD), dynamic light scattering, high heating value, scanning electron microscopy techniques and chemical composition, GM was capable of producing a biomass rich in α‐cellulose (58.0%: SWT2‐C), whereas processed SWT1 and SWT2 through conventional method led to a more percentage of H, β‐ and γ‐C mixtures than α‐polymorphous; 41.0% and 51.0%, respectively. This new method could impact of an important manner to the development of biodegradable thermoplastics. The approximation, from deconvolution of TGA/DTA, led to determine adequately the composition of hemicellulose (SWT1‐C: 51.0%, SWT2‐C: 36.0–0.00%), lignin (SWT1‐C: 17.0%, SWT2‐C: 20.0%) and cellulose (SWT1‐C: 32.0%, SWT2‐C: 44.0%). XRD analysis also indicated that samples contain the following percentage of polymorphous cellulose compounds: SWT1‐C (Type II: 71.3%), SWT2‐C (Type I α: 44.6% and II: 41.4%) and SWT2‐C‐GM (Type II: 38.8%), which confirms that the combination of the type of biomass and the applied pretreatment plays a fundamental role for final applications; in this case, it can be appropriate for elastomers and thermoplastic uses. As a final point, the cellulose composition and thermal stability of both sources is comparable with the commonly used raw material for commercial products.