Rapid and efficient dehydration of cellulose nanofiber hydrogels via electroosmosis

Efficient dehydration of cellulose nanofiber (CNF)/water dispersions and hydrogels is still a challenge in the industrial use of CNFs. In this study, electroosmosis of CNF hydrogels was evaluated as a dehydration method. TEMPO-oxidized CNF hydrogels were rapidly dehydrated by applying DC 20 V, and the CNF concentration increased from 0.5 wt% to ∼10 wt% within 3 min. The energy efficiency of dehydration was more than 7 times greater than that of evaporation, and the resulting concentrated CNF hydrogels were successfully redispersed through a simple neutralization process. In addition, the anisotropic shrinkage of CNF hydrogels due to electroosmosis is suitable for CNF film preparation. This work provides new insights into dehydration methods for CNF/water dispersions and hydrogels. • CNF hydrogels were quickly and efficiently dehydrated via electroosmosis. • The concentration of the CNF hydrogel was increased from 0.5 wt% to ∼10 wt% within 3 min. • After dehydration, the highly concentrated CNF hydrogels could be redispersed through a simple neutralization process. • The anisotropic shrinkage during electroosmotic dehydration is suitable for CNF film preparation.