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Influence of mechanical pretreatment to isolate cellulose nanocrystals by sulfuric acid hydrolysis

Author:
Pirich, Cleverton Luiz, Picheth, Guilherme Fadel, Machado, João Pedro Elias, Sakakibara, Caroline Novak, Martin, Andressa Amado, de Freitas, Rilton Alves, Sierakowski, Maria Rita
Source:
International journal of biological macromolecules 2019 v.130 pp. 622-626
ISSN:
0141-8130
Subject:
acid hydrolysis, cellulose, cellulose nanofibers, crystal structure, grinding, magnetism, mixing, nanocrystals, rheological properties, sulfuric acid, zeta potential
Abstract:
The mechanical pretreatments intensities on characteristics of cellulose nanocrystals (CNC) prior to acid hydrolysis was evaluated. The cellulose was submitted to mechanical pretreatment as: magnetic stirring (CNCst), blending (CNCbl) or grinding by 20 (CNC20x) and 40 (CNC40x) passages in a super mass colloid mill. Then, all samples were submitted to H2SO4 hydrolysis and the CNC were evaluated by total mass yield (TMY%), rheological behavior, size distribution for width/length (WD), crystallinity index (CI%), OSO3− substitution degree (SD) and zeta potential (ζ). After hydrolysis samples exhibited the same SD (190 ± 5 mMol·kg−1), ζ (−55 ± 3 mV) and CI% (65 ± 2), differing only in TMY% and WD. The CNCst showed TMY% of 85%, WD of 8 ± 5 nm and 100–800 nm, with presence of cellulose nanofibers (CNF), suggesting incomplete hydrolysis. The CNCbl and CNC20x revealed TMY% of 65 ± 1, but differed in WD of 8 ± 5 nm and 300 ± 200 nm and 8 ± 5 nm and 200 ± 170 nm, respectively. The results showed that the grinding mechanical pretreatment is mandatory for CNF isolation, but not for CNC. Stability profile after the hydrolytic procedure, CI%, morphology and similar character generated CNC with adequate features and good yield, by simple mechanical stirring or blending, reducing the production's cost and allowing industrial-scale production.
Agid:
6333140