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.

No abstract

The isolation of cellulose nanocrystals (CNCs) by organic acid hydrolysis can contribute to reducing the extensive use of mineral acids, but aspects related to performance, cost effectiveness, and sustainability still need to be addressed. Here, techno-economic analysis (TEA) and life cycle assessment (LCA) were performed to evaluate the production of CNCs using organic and/or inorganic acid hydrolysis, in the context of a sugar cane biorefinery. CNCs were extracted from sugar cane bagasse using sulfuric acid (S-CNC), citric acid (Cit-CNC), and their combination (Cit-S-CNC). The nanodimensional structures were highly dependent on the type of acid used, but all the conditions resulted in nanostructures with CNC characteristics. The minimum product selling price values calculated by TEA for Cit-CNC and Cit-S-CNC were 34.0% and 37.2% higher, respectively, compared to S-CNC, mainly due to the high cost of citric acid recovery. The citric acid hydrolysis and recovery steps had substantial environmental impacts, accounting for up to ∼58% of the gobal warming potential values for Cit-CNC and Cit-S-CNC, which were more than 2fold higher than for S-CNC. These findings showed the importance of using TEA and LCA tools to support decision making in the selection of nanocellulose isolation routes in future biorefineries.

No abstract

No abstract