Butanol-mediated oven-drying of nanocellulose with enhanced dehydration rate and aqueous re-dispersion
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The application potential of nanocellulose has been previously hindered by the costly and slow drying methods that this material requires, including freeze/supercritical drying process. The main issue for nanocellulose commercialization is how effectively and rapidly its high water contents (90–99%) can be removed, all of which raise its transportation and processing costs. Oven-drying is the fastest, most economical, and most scalable method for dehydrating nanocellulose, but causes strong interfibrillar aggregation and leads to poor aqueous re-dispersion. Here, we report that the problems of nanocellulose oven-drying are comprehensively overcome by adding tert-butanol (t-BuOH) to the nanocellulose solution at >90%. In a lab-scale comparison, the t-BuOH-mediated oven-drying of aqueous nanocellulose showed lower drying times by a factor of 2–12 compared to water only oven-drying and freeze drying of the same material. The dispersibility of this dried nanocellulose is as high as the never-dried material in terms of particle size, light transmittance, and sedimentation. t-BuOH reduces interfibrillar shrinkage due to the lower surface tension of t-BuOH compared to water, and a remaining t-BuOH/water mixture decreases interfibrillar adhesion and contact.
KeywordsNanocellulose Oven-drying Co-solvent Drying rate tert-Butanol Re-dispersion
This work was financially supported by the Technology Innovation Program (10070150) funded by the Ministry of Trade, Industry and Energy (MOTIE, Korea), and partially supported by a grant from Research Center for Chemical Biotechnology of Korea Research Institute of Chemical Technology (SI 1709).
All authors have given approval to the final version of the manuscript. Z. H. and H. J. conducted the experiments. H. J., J. J., S. Y. H., J. P., and D. X. O. wrote the manuscript. S. P. and S. K. conducted supplementary experiments and literature survey.
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