(192g) Evaluation and Optimization of Biofuel Production Fromsunflower Hulls Using Central Composite Design Analysis

Authors: 
Kamireddy, S. R., University of North Dakota
Schaefer, C., University of North Dakota
Ji, Y., University of North Dakota


The
annual production of sunflower seeds in USA is around 1.8 million metric tons.
Sunflower seeds are used mostly in the production of edible oil. This results
in large amount of sunflower hulls and stalks during the industrial processing.
 Sunflower hulls have less commercial value and these hulls decompose very
slowly. Sunflower hulls mainly consist of cellulose, hemicellulose and lignin and
the presence of these compounds is a major driving force for biofuel research. The
sunflower hull is rich in 5-carbon (C-5) and c-carbon (C-6) sugars that are
ideal for the production of advanced biofuels. The objective of this project is
to evaluate
and optimize the biofuel production from sunflower hulls as a non-food resource
and
thus improve
the local economy and reduce the dependence of our nation on
foreign sources of energy.

This
project is divided into two sections (pretreatment
and enzymatic hydrolysis) to evaluate the
sunflower hull as a potential biofuel feedstock. Sunflower hulls are
pulverized to an average particle size between 0.1 mm to 0.5 mm using Wiley
mill.  Extractives in the sunflower hulls will be removed by both water
extraction and ethanol extraction using Soxhlet apparatus. Raw sunflower hulls
compositional analysis will be performed by using NREL LAP procedures. The sunflower hull pretreatment uses dilute
sulfuric acid at 160°C, 0.5% sulfuric acid and 10 minutes residence
time. Structural carbohydrates of all slurry samples will be analyzed using
Agilent 1200 High Performance Liquid Chromatography (HPLC)
and acid soluble lignin will be evaluated by Thermo Scientific Evolution 600
UV-VIS Spectroscopy. The enzymatic hydrolysis will be conducted using central composite design method.  The experiments will be performed at different enzyme loadings (5, 10, and 20 mg/g biomass),
different reaction temperatures (40, 50 and 60°C) and different solid contents
(1%, 5%, and 10%). The enzymatic digestibility of
the pretreated solids will be measured to evaluate
the enzyme accessibility and yield. A comparision study of hulls will be done
using GC 220 and Accellerase 1500 enzymes supplied by Genencor.