Volume 7, Issue 4 (April 2010)
Compositional Analysis of Microwave Chemically Treated Biomass Samples
The compositional analysis of slurries generated from the microwave-assisted pretreatment of switchgrass, prairie cordgrass, and distillers dried grains with solubles were investigated. The biomass samples were treated under acidic, alkali or neutral conditions at 1200 W and 200°C for 10 min. The supernatants were analyzed for sugars, whereas the compositional analysis of the remaining solid fractions was performed using an integrated scheme based on the Standard Laboratory Analytical Procedures for raw biomass developed at the National Renewable Energy Laboratory. The experimental results show that little to no arabinose was found in these treated substrates. Substrates treated under alkaline conditions resulted in the highest carbohydrate content with the lowest lignin amount, whereas acidic pretreatments with 0.5 % H2SO4 resulted in hemicellulose-free biomass. A minute amount of hemicellulose was still present in prairie cordgrass and switchgrass after treatment with 0.2 % H2SO4 and this amount increased for pretreatments with H2O and 0.3 % H2O2. Pretreatments under alkaline conditions with 1 % NaOH were the least aggressive treatments methods because they retained the most carbohydrates in the biomass pulp while having the lowest lignin amount.