The transformation of lignocellulosic biomass into biofuels represents an interesting and sustainable alternative to fossil fuel for the near future. However, one still faces some major challenges for the technology to be fully realized including feedstock costs, novel pretreatment processes, production, transportation, and environmental impact of the full chain. The development of new technologies focused to increase the efficiency of cellulose conversion to biofuels determines successful implementation. Mechanical fractionation is an essential step in order to increase final carbohydrate output, appropriate particle sizes and densification, enzymatic accessibility, and bioconversion affectivity without the production of toxic side streams. In this review article, we surveyed a substantial amount of previous work in mechanical fractionation or pretreatments of a variety of lignocellulosic biomasses; these include numerous milling schemes and extrusions, and their impacts on the physical and physicochemical properties of the lignocellulosic matrix (crystallinity, surface area, particle size, etc). We have also compared results with other pure chemical and physicochemical pretreatments in order to show the new aspects and advantages/disadvantages of such an approach. Last, but not least, the effec
Additive manufacturing or 3D printing has the potential to displace some of the current manufacturing techniques and is particularly attractive if local renewable waste resources can be used. In this study, rice husk, and wood powders were compounded in polylactic acid (PLA) by twin screw extrusion to produce filaments for fused-deposition modeling 3D printing. The biomasses were characterized in terms of physical features (e.g., particle size, density) and chemical compositions (e.g., solid state nuclear magnetic resonance, ash content). The two biomasses were found to have a different impact on the rheological behavior of the compounds and the extrusion process overall stability. When comparing the complex viscosity of neat PLA to the biomass/PLA compounds, the integration of wood powder increased the complex viscosity of the compound, whereas the integration of rice husk powder decreased it. This significant difference in rheological behavior was attributed to the higher specific surface area (and chemical reactivity) of the rice husk particles and the presence of silica in rice husks compared to the wood powder. Color variations were also observed. Despite the biomass filler and rheological behavior differences, the mechanical properties of the 3D printed samples were similar and predominantly affected by the printing direction.
The comminution of lignocellulosic biomass is a key operation for many applications as bio-based materials, bio-energy or green chemistry. The grinder used can have a significant impact on the properties of the ground powders, of those of the end-products and on the energy consumption. Since several years, the milling of lignocellulosic biomass has been the subject of numerous studies most often focused on specific materials and/or applications but there is still a lack of generic knowledge about the relation between the histological structure of the raw materials, the milling technologies and the physical and chemical properties of the powders. This review aims to point out the main process parameters and plant raw material properties that influence the milling operation and their consequences on the properties of ground powders and on the energy consumption during the comminution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.