Micromorphological changes and mechanism associated with wet ball milling of Pinus radiata substrate and consequences for saccharification at low enzyme loading. (August 2016)

• Record Type: Journal Article
• Authors: Vaidya, Alankar A.; Donaldson, Lloyd A.; Newman, Roger H.; Suckling, Ian D.; Campion, Sylke H.; Lloyd, John A.; Murton, Karl D.
• Is Part Of: Bioresource technology. Volume 214(2016)
• Page Start: 132
• Page End: 137
• Publication Date: 2016-08
• Subjects: Ball milling -- Enzymatic saccharification -- Microscopy -- Pretreatment -- Softwood; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2016.04.084
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: Wet ball milling can provide high cellulose digestibility at low enzyme loadings. Micromorphological changes with milling time are characterized by SEM and 13 C NMR. A mechanism of ball milling proposed based on actual micromorphological changes. Proposed mathematical model supports the mechanism of wet ball milling. Abstract: In this work, substrates prepared from thermo-mechanical treatment of Pinus radiata chips were vibratory ball milled for different times. In subsequent enzymatic hydrolysis, percent glucan conversion passed through a maximum value at a milling time of around 120 min and then declined. Scanning electron microscopy revealed breakage of fibers to porous fragments in which lamellae and fibrils were exposed during ball milling. Over-milling caused compression of the porous fragments to compact globular particles with a granular texture, decreasing accessibility to enzymes. Carbon-13 NMR spectroscopy showed partial loss of interior cellulose in crystallites, leveling off once fiber breakage was complete. A mathematical model based on observed micromorphological changes supports ball milling mechanism. At a low enzyme loading of 2 FPU/g of substrate and milling time of 120 min gave a total monomeric sugar yield of 306 g/kg of pulp which is higher than conventional pretreatment method such as steam exploded wood.