Defibrillated Celluloses via Dual Twin-Screw Extrusion and Microwave Hydrothermal Treatment of Spent Pea Biomass

Abstract

The defibrillation of lignocellulosic matter from pea waste using a dual approach of twin-screw extrusion and microwave hydrothermal treatment (MHT) in the presence of water alone from to 200 o C is reported. Gradual "scissoring" of biomass macrofibres to microfibrils was observed alluding to the Hy-MASS (Hydrothermal Microwave-assisted Selective Scissoring) concept. The morphology and properties of two types of MFC: PEA (non-extruded) and EPEA (extruded) were compared. The EPEA samples gave higher crystallinity index and thermal stability, reduced lignin and hemicellulose content, narrower fibril width, better water holding capacity slightly and higher surface area compared with their non-extruded counterparts (PEA). Twin screw extrusion as a pretreatment method followed by MHT represents a potential way to produce microfibrillated cellulose with improved physical performance from complex biomass sources.

Microwave-Assisted Defibrillation of Microalgae

“…In contrast to glucuronic acid, the concentration of mannitol, levoglucosan and xylose was much lower but, nevertheless, increased with increasing temperature, peaking at 160 °C (standard method, levoglucosan), 180 °C (standard method, mannitol) and 200 °C (standard method, xylose). The formation of these sugars along with formic acid, furfural and acetic acid is consistent with the high temperature hydrolysis of cellulose and hemicellulose [ 13 , 14 , 16 ]. Furthermore, the concentration of lactic acid increased with increasing microwave temperature: again, this is consistent with depolymerization of carbohydrates [ 13 , 14 , 16 ].…”

“…Both the standard method and the scCO 2 method result in similar MFC yields within a margin of fewer than 5% of each other, suggesting a limited effect of the supercritical treatment on MFC yield. Analogous with the degradation and defibrillation of cellulose, the carbohydrate yield similarly increases, as expected, in linear fashion, from 6% to a maximum of 22% [ 13 , 14 , 16 ].…”

“…Defibrillated celluloses in the form of micro- and nanocellulose are gaining significant importance because of their interesting functional properties: high colloidal stability, high thermal stability, and high mechanical strength. Thus, these materials are useful in a wide range of applications, for example, coatings, optically transparent materials, aerogels, rheology modifiers, electronics, filters, packaging, or molecular scaffolding [ 14 ].…”

“…Traditionally nanocellulose is produced via intensive chemical and mechanical processing of high cellulosic content biomass, such as, wood pulp [ 14 , 15 ]. Microwave hydrothermal treatment is considered a fast and less energy intensive method than traditional approaches, enabling the production of defibrillated celluloses without the use of any chemical or biological additives.…”

“…The removal of hemicellulose, pectins, and amorphous cellulose is induced through microwave energy, resulting in defibrillated cellulose fibres with a high degree of crystallinity. This process has been successfully achieved in a range of biomass types including orange peel [ 13 ], spent ginger waste [ 16 ], and spent pea biomass [ 14 ]. The microwave-assisted hydrolysis of hemicellulose, entangling the cellulose microfibrils, was achieved below 180 °C, whereas beyond 180 °C, the hydrolysis of amorphous cellulose and the dispersion of cellulosic fibres were witnessed [ 13 , 14 , 16 ].…”