Concentration of Cellulose Nanofiber Dispersion by Osmosis

Cellulose nanofiber (CNF) has recently emerged as a promising new bio-nanomaterial. Typically, a dispersion of CNFs with a high water content is prepared by chemical and/or mechanical treatment. A rapid water removing method of the CNF dispersion should be developed for its use. In this study, a new method to concentrate the CNF dispersion was investigated by using osmosis with a sucrose solution. This method achieved a concentration of 1 wt％ dispersion of CNF into 19 wt％. The sucrose was also present in the concentrated CNF dispersion after osmosis. The concentration rate at 50 ̊C was higher than that at 23 ̊C. The concentration depended on the cutoff size of the molecular weight for the porous membrane. The porous membrane with a low-molecular-weight cutoff suppressed the amount of sucrose in the concentrated CNF dispersion, and increased the maximum CNF concentration of the CNF dispersion after osmosis.