Butanol-mediated oven-drying of nanocellulose with enhanced dehydration rate and aqueous re-dispersion.

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 <italic>tert-</italic>butanol (<italic>t-</italic>BuOH) to the nanocellulose solution at >90%. In a lab-scale comparison, the <italic>t-</italic>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. <italic>t-</italic>BuOH reduces interfibrillar shrinkage due to the lower surface tension of <italic>t-</italic>BuOH compared to water, and a remaining <italic>t-</italic>BuOH/water mixture decreases interfibrillar adhesion and contact.This paper suggests a strategy to improve the aqueous re-dispersibility of oven-dried nanocellulose, and to accelerate oven-drying rate.<graphic></graphic> [ABSTRACT FROM AUTHOR]