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.
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