(602an) Effect of Particle Size On Enzymatic Hydrolysis of Pretreated Miscanthus

Effect of
Particle Size on Enzymatic Hydrolysis of Pretreated Miscanthus

Esha Khullar¹, Bruce S. Dien²,
Kent D. Rausch¹, M. E. Tumbleson¹ and Vijay Singh^1*

¹University of Illinois at Urbana-Champaign, Urbana, IL 61801

(217-333-9510) vsingh@uiuc.edu
and ²National Center for Agricultural Utilization Research, ARS,
USDA, Peoria, IL 61604

The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was
determined.  Miscanthus was ground using a hammer mill equipped with screens
having 0.08, 2.0 or 6.0 mm sieve openings. 
Particle size distribution and geometric mean diameters were determined
for all samples.  Ground samples
were subjected to hot water, dilute acid or dilute ammonium hydroxide
pretreatment.  Enzyme hydrolysis was
conducted on washed pretreated solids; sugar generation was used as a measure
for pretreatment efficiency.  Glucose
and xylose concentrations were monitored using HPLC.  Glucose and xylose profiles were
generated and hydrolysis rates estimated. 
Glucan, xylan and total conversion yields were determined by comparing
final sugar concentrations obtained to theoretical amounts present in raw
biomass. 

Geometric mean diameters were the smallest from 0.08 mm sieve
screen (56 μm) followed by 2.0 mm (301 μm) and 6.0 mm (695 μm)
screens.  Across all pretreatments,
an increase in total polysaccharide conversion (12 to 26%) was observed when
particle size was decreased from 6.0 mm to 0.08 mm.  Enzyme hydrolysis of unpretreated biomass samples also resulted in increased
total conversions as particle size decreased, although mean conversions (10 to
20%) were much lower than for pretreated biomass samples (40 to 70%),
indicating the need for chemical pretreatments in biomass conversion.