%0 Journal Article
%T Optimizing carboxylated nanocellulose preparation: A kinetic and mechanistic study on the enhancement of TEMPO-mediated oxidation via swelling treatment.
%A Cai C
%A Wang G
%A Bai X
%A Xu D
%A Yan C
%A Yang Y
%J Int J Biol Macromol
%V 274
%N 0
%D 2024 Jun 21
%M 38908641
%F 8.025
%R 10.1016/j.ijbiomac.2024.133342
%X This study explored the application of swelling pretreatment as a solution to the high cost and contamination associated with the process of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation for nanocellulose preparation. The results demonstrated that swelling significantly expanded the fibers while preserving the degree of polymerization (DP) of cellulose (approximately 95 %). The native crystal structure and hydrogen bonding of cellulose were disrupted after swelling, leading to a reduction in crystallinity and crystallite size, and the decrease of bonding energy and content of intermolecular O6-H⋯O3'. The TEMPO-mediated oxidation processes of cellulose fibers with or without swelling were successfully fitted using a consecutive first-order reaction kinetic model. The fitting results indicated that swelling significantly reduced the activation energy of TEMPO-mediated oxidation and enhanced the reaction rate. Among three swelling systems, the NaOH/thiourea/water system exhibited the optimal promotion effect. Consequently, the swelling treatment enables a significant reduction of 30 % in the catalyst dose for the TEMPO-mediated oxidation while preserving a competitive reaction rate, yield, and product performance. Lower catalyst dosage helps to reduce cost and environmental impact, facilitating the industrial application of the TEMPO-mediated oxidation process.