Evaluation and Optimization of Biofuel Production Fromsunflower Hulls Using Central Composite Design Analysis

Monday, October 17, 2011
Exhibit Hall B (Minneapolis Convention Center)
Srinivas Reddy Kamireddy, Christopher Schaefer and Yun Ji, Chemical Engineering, University of North Dakota, Grand Forks, ND

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 160C, 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 60C) 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.


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