Cellulose nanocrystals' production in near theoretical yields by 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4) – mediated hydrolysis. (6th March 2015)

• Record Type: Journal Article
• Authors: Mao, Jia; Heck, Barbara; Reiter, Günter; Laborie, Marie-Pierre
• Is Part Of: Carbohydrate polymers. Volume 117(2015)
• Page Start: 443
• Page End: 451
• Publication Date: 2015-03-06
• Subjects: Cellulose nanocrystals -- Ionic liquids -- Reaction severity yield optimization; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2014.10.001
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: A novel one pot hydrolysis is proposed with a mildly acidic aqueous ionic liquid by decoupling a swelling step from the hydrolysis reaction. Near theoretical yields for the production of cellulose nanocrystals are achieved for the first time in a mild procedure from common cellulosic sources, viz. wood pulps and microcrystalline cellulose. Successive Taguchi experimental plans allow identifying and optimizing reaction parameters in a minimum number of experiments. The combined severity factor (CSF), [H+]/[AGU] molar ratio and crystalline region recovery (CR) are optimized allowing to achieve excellent recovery of native monocrystals under mild hydrolysis conditions. Abstract: We report on near theoretical yield production of cellulose I nanocrystals (CNCs) using a two-step hydrolysis with the mildly acidic ionic liquid (IL) 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO4 ) in aqueous solution from common cellulosic sources. Two successive Taguchi experimental plans were performed to evaluate the impact of selected reaction parameters ( T, t, H2 O:IL ratio) and their interactions on the CNCs' yield from bleached softwood kraft pulp (SWP), bleached hardwood kraft pulp (HWP) and microcrystalline cellulose (MCC). With these experimental plans, the molar yield for extraction of nanocrystals was optimized to near theoretical levels, reaching 57.7 ± 3.0%, 57.0 ± 2.0%, and 75.6 ± 3.0%, for SWP, HWP and MCC, respectively. The reaction yields corresponded to a relative crystalline region recovery of 84.1 ± 5.3%, 71.7 ± 1.3%, 76.0 ± 2.0% from SWP, HWP and MCC, respectively. The collected nanocrystals exhibited high aspect ratios (36–43), negligible sulfur content (0.02–0.21%) and high solvent dispersibility in comparison to those obtained with the traditional sulfuric acid method. Additionally these near theoretical yields were achieved for mild reaction conditions with the combined severity factor of 2 and 3 for MCC and pulp, respectively. Overall this two-stage IL-mediated preparation of nanocrystals combines the advantages of achieving high product quality, high reaction yields and mild conditions.