US 12,320,069 B2
Carboxylated cellulose nanofiber and preparation method thereof
Haipeng Yu, Harbin (CN); Xiaochao Shi, Harbin (CN); and Qinqin Xia, Harbin (CN)
Assigned to Northeast Forestry University, Harbin (CN)
Filed by Northeast Forestry University, Harbin (CN)
Filed on Dec. 20, 2022, as Appl. No. 18/068,847.
Claims priority of application No. CN202111600313.7 (CN), filed on Dec. 24, 2021.
Prior Publication US 2023/0160146 A1, May 25, 2023
Int. Cl. D21H 11/20 (2006.01); D21C 9/00 (2006.01); D21H 11/18 (2006.01)
CPC D21H 11/20 (2013.01) [D21C 9/005 (2013.01); D21H 11/18 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A method for preparing a carboxylated cellulose nanofiber, comprising:
(1) mixing choline chloride, citric acid and water at 60-100° C. for 15-60 minutes to obtain a hydrated multi-carboxylic acid deep eutectic solvent;
(2) mixing the hydrated multi-carboxylic acid deep eutectic solvent with cellulose followed by hydrolysis-esterification reaction at 120-130° C. for 2-3 hours to obtain a carboxylated cellulose; and
(3) mixing the carboxylated cellulose and water followed by nano-fibrillation to obtain the carboxylated cellulose nanofiber;
wherein in step (1), a ratio of a weight of the water to a total weight of the choline chloride and the citric acid is (0.25˜4):1; and a molar ratio of the choline chloride to the citric acid is 1:(1˜4);
the carboxylated cellulose nanofiber has a carboxyl content of 0.23˜1.45 mmol/g, and an aspect ratio of 1000˜4000; and
the nano-fibrillation is performed under an ultrasonic power of 600-1000 Watts for minutes min.