A novel process to isolate fibrils from cellulose fibers by high‐intensity ultrasonication, Part 1: Process optimization

Abstract

Cellulose fibrils of microscale and nanoscale sizes have great strength and hence furnish the possibility of reinforcing polymers. Fibrils can be isolated from natural cellulose fibers by chemical or mechanical methods. However, the existing procedures either produce low yields or severely degrade the cellulose and, moreover, are not environment friendly or energy efficient. The purpose of this study was to develop a novel process that uses high-intensity ultrasonication (HIUS) to isolate fibrils from several cellulose resources. Six factors that may affect the efficiency of fibrillation, including power, temperature, time, concentration, size, and distance, have been considered and discussed. HIUS treatment can produce very strong mechanical oscillating power; therefore, the separation of cellulose fibrils from its biomass is possible by the action of hydrodynamic forces of the ultrasound. Water-retention value and volume change were used to evaluate and optimize the process parameters. The degree of fibrillation of the cellulose fibers treated by HIUS was significantly increased.

Rice Straw Cellulose Nanofibrils via Aqueous Counter Collision and Differential Centrifugation and Their Self-Assembled Structures

“…34 The 58.4% yield of the finest F4 CNFs in the last supernatant (centrifuged at 20,800g) was nearly double that from the microfluidizer treated softwood kraft pulp (29.4% centrifuged at 10,000g) 35 while with only one-fourth of the energy input (15 vs 55.3 MWh/t) or 1.5 times of that from grinding eucalyptus kraft pulp 33 and also with only one-third of energy consumption (15 vs 40 kWh/kg). The lower energy required to defibrillate rice straw cellulose by ACC and the high CNF yields clearly demonstrate ACC to be a more energyefficient way to generate cellulose nanofibrils from rice straw than other mechanical means from wood pulp.…”

“…Avicel CNFs from high-intensity ultrasonication for 60 min (centrifuged at 900g) 33 and 40% bleached eucalyptus kraft pulp CNFs from grinding with an energy input of 40 kWh/kg (centrifuged at 200g). 34 The 58.4% yield of the finest F4 CNFs in the last supernatant (centrifuged at 20,800g) was nearly double that from the microfluidizer treated softwood kraft pulp (29.4% centrifuged at 10,000g) 35 while with only one-fourth of the energy input (15 vs 55.3 MWh/t) or 1.5 times of that from grinding eucalyptus kraft pulp 33 and also with only one-third of energy consumption (15 vs 40 kWh/kg).…”

Effect of nanocellulose isolation techniques on the formation of reinforced poly(vinyl alcohol) nanocomposite films

“…While for mechanical methods, which include high intensity ultrasonication [13], high pressure refiner [14] or grinder treatment [15], the main product generated is not a single fiber and has been referred as nanofibrils. However, these two techniques of extracting nanocellulose from plants are time consuming and very costly [1].…”

Advanced Cellulosic Nanocomposite Materials

“…Several tools can be used for morphological observation, such as a scanning electron microscope (SEM), an atomic force microscope (AFM), and a transmission electron microscopy (TEM) (Bhatnagar and Sain, 2005;Bondeson et al, 2006;Chakraborty et al, 2005;Choi and Simonsen, 2006;Wang and Sain, 2007;Zimmermann et al, 2004). The degree of fibrillation of the fibers used to isolate MFC/microfibrils/aggregates by mechanical methods may be evaluated by water retention value (WRV) (Cheng et al, 2007a;Cheng et al, 2010a, b;Herrick et al, 1983;Turbak et al, 1983;Wang and Cheng, 2009;Yano and Nakahara, 2004). Wide angle X-ray diffraction (WAXD) is used to study the crystallinity of the fibrils (Bhatnagar and Sain, 2005;Chakraborty et al, 2006;Cheng et al, 2007a;Gindl and Keckes, 2005).…”