Carboxymethyl Cellulose Enhanced Production of Cellulose Nanofibrils

Yunsang Kim,Corbin Feit,Sergiy Minko,Suraj Sharma,Lauren T Mccoy,Shuaib A Mubarak

doi:10.3390/fib9090057

Yunsang Kim, Corbin Feit + Show 4 more

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https://doi.org/10.3390/fib9090057

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Abstract

Cellulose nanofibrils (CNF) were produced by high-pressure homogenization from kraft pulp in the presence of carboxymethyl cellulose (CMC) of varying molecular weights. CNF pretreated with 250 kD CMC exhibited the maximum specific surface area (SSA) of 641 m2/g, which is comparable to that of CNF pretreated by 2,2,6,6-tetramethyl-piperidinyl-1-oxyl (TEMPO)-meditated oxidation with a high degree of fibrillation. Rheological and microscopic analyses also indicated a high level of fibrillation for the CMC-pretreated CNF. In contrast, the reference CNF without the CMC pretreatment showed a lower level of fibrillation, which was reflected in decreased viscosity and the reduction of SSA by a factor of 19. With the high-degree fibrillation and low toxicity, the CMC pretreatment is a promising method for the production of high-quality CNF in an environmentally friendly way.

Highlights

Originating primarily from wood and plant biomass, cellulose is one of the most abundant natural polymers that exhibits sustainability; biocompatibility; and low environmental, health, and safety concerns
Nanocellulose (NC) is engineered nano-structured cellulose, which is categorized into cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), and bacterial nanocellulose (BNC) depending on the size of NC particles and individualization methods [1]
CNF consists of nano-sized cellulosic fibrils, which are generally produced by the delamination of native cellulose fibers (>1 mm in length and >10 μm in width) from wood and plant biomass

Summary

Introduction

Originating primarily from wood and plant biomass, cellulose is one of the most abundant natural polymers that exhibits sustainability; biocompatibility; and low environmental, health, and safety concerns. CNF consists of nano-sized cellulosic fibrils, which are generally produced by the delamination of native cellulose fibers (>1 mm in length and >10 μm in width) from wood and plant biomass. Mechanical refining processes—such as highpressure homogenization, microfluidization, ultrasonication, and cryocrushing—are often combined with various pretreatments of cellulose fibers to increase the degree of fibrillation and reduce the energy consumption [18,19,20]. Carboxylate moieties on the surface of cellulose fibers can weaken inter- and intra-fiber hydrogen bonds by repulsive electrostatic force, which facilitates the individualization of nano-sized cellulose fibrils (CNF) during the mechanical refining process [27]. Unlike acid hydrolysis used for the production of CNC, these pretreatments selectively modify the surface of cellulose fibers, retaining the crystallinity and the length of cellulose fibrils after the individualization [27,28]. The use of harmful solvents and chemicals likely incurs substantial environmental costs for the large-scale production of CNF [29,30]

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