The application of green process engineering strategies to obtain high-value, eco-friendly, and biodegradable materials from residual lignocellulosic biomass can contribute to the sustainability of future biorefineries. Here, we investigated the potential of sugarcane bagasse and straw as lignocellulosic biomass feedstocks to obtain nanocellulose, using the enzymatic hydrolysis route as a platform. The fibers were submitted to a purification process followed by enzymatic hydrolysis with a commercial enzyme cocktail. The cellulose nanomaterials obtained from both fibers (sugarcane bagasse and straw) presented a high crystallinity index (∼70%) and thermal stability (degradation onset temperatures higher than 300 °C). After the enzymatic hydrolysis, a centrifugation step was used to separate the cellulose nanocrystals (CNC) present in the nanocellulose samples. The increase of the duration of enzymatic hydrolysis resulted in an increase of the CNC content and decreases in the diameter and length of the CNC. These findings indicated the potential of using the enzymatic route as a platform to obtain nanocellulose as a value-added bioproduct from both sugarcane bagasse and straw. In addition to being eco-friendly, this process also releases a stream rich in soluble sugars that can be used to produce ethanol or other biobased products, within the biorefinery concept.

Nanocellulosic materials, either as cellulose nanofibrils (CNF) or cellulose nanocrystals (CNC), have a wide range of potential applications in different industrial sectors, due to their renewable nature and remarkable properties. Here, a sustainable and environmentally friendly method to obtain nanocellulose was evaluated using hydrolysis with citric acid, an organic acid that can be obtained as a biorefinery product. This approach resulted in a single-step extraction of nanocellulose, with carboxyl functionalization of the surface varying according to hydrolysis reaction times from 1.5 to 6 h, at 120 °C, as evidenced using NMR to measure the degree of substitution. The charged surface groups of CNC and CNF resulted in improved colloidal stability, with ζ-potential values from −36 to −48 mV. Both CNC and CNF extracted using different reaction times were thermally stable, but the increase of carboxyl groups reduced the degradation temperature. Techno-economic analysis (TEA) showed that the cost of citric acid had the greatest influence on the minimum product selling price (MPSP) of the nanocellulose, indicating that the production of citric acid within the biorefinery could be an interesting way to make this approach feasible.

This work proposes modifying the adding sequence of components during the production of poly(lactic acid) (PLA) and poly(ε‐caprolactone) (PCL) ternary systems with multiwalled carbon nanotubes (CNT) or graphene nanoplatelets (GN), in order to analyze the nanoparticles’ selective localization in terms of the competition between different factors, such as kinetics, thermodynamics, rheology, and geometry. In the studied system, the PLA's viscosity is higher than the PCL's and the difference in interactions between the CNT or the GN/PLA and the CNT or the GN/PCL is small, meaning the viscosity effects could dominate. However, other factors, such as thermodynamics and geometry, can be observed to compete with the rheological factor, depending on the mixing sequences. Depending on the processing time, a competition between thermodynamics and rheological factors could be observed when the nanoparticles had contact first with the thermodynamically favored phase. The competition between geometrical and rheological factors was observed in the presence of GN in the PLA phase, in the system in which the GN was added first to the PLA phase, which is the phase of lowest affinity. POLYM. ENG. SCI., 59:323–329, 2019. © 2018 Society of Plastics Engineers