Dehydration of collagen hydrogel simply by immersion in sodium carboxymethylcellulose solution

Pre-dehydration of collagen-based hydrogel can result in reduced energy consumption in their large-scale production. This article reported a method to dehydrate collagen hydrogel by simply immersing hydrogel into sodium carboxymethylcellulose (CMC) solution, and the dehydration regularity and possible dehydration mechanisms were investigated. Collagen hydrogel was dehydrated in CMC solution with a dehydration rate of up to 68%, which favored the subsequent drying process as the drying time reduced by at least 18%. The CMC concentration, degree of substitution (DS), molecular weight (MW), and immersion time were all important factors affecting dehydration performance. The main dehydration mechanism was shown to be the Donnan equilibrium, which was attributed to the semi-permeability of the collagen hydrogel and the osmotic pressure difference at the interface induced by the CMC. Low MW CMC was able to penetrate into collagen hydrogel while high MW CMC was still difficult in penetrating into collagen hydrogel even in prolonged immersion time. Moreover, CMC-induced dehydration did not change the collagen fiber structures. This study provides a new pathway for the pre-dehydration of collagen-based materials, and also can help the design of collagen gel materials.