Microwave-assisted extraction of lignin from triticale straw: Optimization and microwave effects

Presently lignin is used as fuel but recent interests in biomaterials encourage the use of this polymer as a renewable feedstock in manufacturing. The present study was undertaken to explore the potential applicability of microwaves to isolate lignin from agricultural residues. A central composite design (CCD) was used to optimize the processing conditions for the microwave (MW)-assisted extraction of lignin from triticale straw. Maximal lignin yield (91%) was found when using 92% EtOH, 0.64 N H2SO4, and 148 degrees C. The yield and chemical structure of MW-extracted lignin were compared to those of lignin extracted with conventional heating. Under similar conditions. MW irradiation led to higher lignin yields, lignins of lower sugar content, and lignins of smaller molecular weights. Except for these differences the lignins resulting from both types of heating exhibited comparable chemical structures. The present findings should provide a clean source of lignin for potential testing in manufacturing of biomaterials. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.