BioChem - DOS

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

Bioresource technology : biomass, bioenergy, biowastes, conversion technologies, biotransformations, production technologies

Vaidya, Alankar A.; Donaldson, Lloyd A.; Newman, Roger H.; Suckling, Ian D.; Campion, Sylke H.; Lloyd, John A.; Murton, Karl D.

<P><B>Abstract</B></P> <P>In this work, substrates prepared from thermo-mechanical treatment of <I>Pinus radiata</I> 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 120min 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 2FPU/g of substrate and milling time of 120min gave a total monomeric sugar yield of 306g/kg of pulp which is higher than conventional pretreatment method such as steam exploded wood.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Wet ball milling can provide high cellulose digestibility at low enzyme loadings. </LI> <LI> Micromorphological changes with milling time are characterized by SEM and <SUP>13</SUP>C NMR. </LI> <LI> A mechanism of ball milling proposed based on actual micromorphological changes. </LI> <LI> Proposed mathematical model supports the mechanism of wet ball milling. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

2016

Elsevier

0960-8524

214

pp.132-137

10.1016/j.biortech.2016.04.084

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART75722551

Ball milling; Enzymatic saccharification; Microscopy; Pretreatment; Softwood