The physicochemical properties of cassava residues subjected to microwave (or steam)-heated acid pretreatment (MHAP or SHAP) were comparatively investigated to improve fermentative hydrogen and methane cogeneration. The hydrogen yield from cassava residues with MHAP and enzymolysis was higher (106.2. mL/g TVS) than that with SHAP and enzymolysis (102.1. mL/g TVS), whereas the subsequent methane yields showed opposite results (75.4 and 93.2. mL/g TVS). Total energy conversion efficiency increased to 24.7%. Scanning electron microscopy images revealed MHAP generated numerous regular micropores (~6. μm) and SHAP generated irregular fragments (~23. μm) in the destroyed lignocellulose matrix. Transmission electron microscopy images showed SHAP generated wider cracks (~0.2. μm) in delaminated cell walls than MHAP (~0.1. μm). X-ray diffraction patterns indicated MHAP caused a higher crystallinity index (33.00) than SHAP (25.88), due to the deconstruction of amorphous cellulose. Fourier transform infrared spectroscopy indicated MHAP caused a higher crystallinity coefficient (1.20) than SHAP (1.12).
Bibliographical noteFunding Information:
This study was supported by the National Natural Science Foundation – China ( 51176163 , 51476141 ), National High Technology R&D Program – China ( 2012AA050101 ), International Sci. & Tech. Cooperation Program – China ( 2012DFG61770 ), Zhejiang Provincial Natural Science Foundation – China ( LR14E060002 ), Program for New Century Excellent Talents in University – China ( NCET-11-0446 ), Specialized Research Fund for the Doctoral Program of Higher Education – China ( 20110101110021 ), Science and Technology Project of Guangxi Province – China ( 1346011-1 ) and Program of Introducing Talents of Discipline to University – China ( B08026 ).
© 2014 Elsevier Ltd.
- Cassava residue
- Microwave-heated acid
- Steam-heated acid