Isolating cellulose nanofibers from steam-explosion pretreated corncobs using mild mechanochemical treatments

Abstract

Cellulose nanofibers (CNFs) with an average diameter 8 nm were isolated from corncobs using a stepwise method that included steam-explosion pretreatment, alkaline treatment, sodium hypochlorite bleaching, high-speed blending, and ultrasonic treatment. This mechanochemical method used only two chemical reagents in low concentrations to remove non-cellulosic components. The removal of non-cellulosic components was confirmed by Fourier-transform infrared spectroscopy. X-ray diffraction revealed an increase in crystallinity during steam explosion and subsequent mechanochemical treatments. Pretreatment by steam explosion caused the partial hydrolysis of hemicellulose and loosened the structure of raw materials, which facilitated the subsequent chemical processes. The thermal stability and morphology of samples at different stages were also investigated. Steam explosion increased the thermal stability of hemicellulose and cellulose components, as it removed a fraction of hemicellulose. High-speed blending reduced the entanglement of cellulosic fibers and created uniform size. Ultrasonic treatment was used in the final step of nanoscale fibrillation. The method used in this study is environmentally friendly and has the potential to be applied at industrial scale.

Effects of steam explosion treatment on the physicochemical properties and biological activities of okara‐derived soluble dietary fibre

“…Both samples exhibited major diffraction intensities at 23.8° 2θ and the peak of SE‐SDF became slightly sharper than that of O‐SDF, indicating SE had little effect on the crystallinity. This was in agreement with the another report that the crystallinity of nanofibers remained largely unchanged after SE (Yang et al ., 2017).…”

Emerging trends in the appliance of ultrasonic technology for valorization of agricultural residue into versatile products

“…The ultrasound treatment applies to the preparation or assisting of valuable materials production from agro-residues such as cellulose nanocrystals (CNC), cellulose nanofibers (CNF), reducing sugars, lignin nanoparticles, chitosan, biochar, biodiesel, etc. [76] , [77] , [78] , [79] , [80] , [81] . Below are the literature studies on producing a value-added product from agro-residue.…”

“…CNF’s applications are utilized widely in coatings, sensors biocomposites, automotive, food packaging, and paper-strength additives [89] , [90] , [91] . The frequent pretreatment method for cellulose extraction commonly involves multi-stage pretreatment for cellulose isolation [78] , [92] , [92] . Ultrasonication is the process method which having a similar mechanism in the fibrillation process as microfluidizer, homogenizer, or mechanical grinding for CNF production.…”

“…The output of ultrasonication’s power was conducted at 1000 W in 30 min. [78] Bamboo Ultrasonication-assisted microwave liquefaction act as a nanofibrillation process. Cellulose nanofibers were isolated by ultrasonic fibrillation of the chemically purified cellulose.…”