Properties and pyrolysis behavior of moso bamboo sawdust after microwave-assisted acid pretreatment

The effects of microwave-assisted acid pretreatment on the characteristics and pyrolysis behavior of moso bamboo sawdust (BS) were investigated by ultimate, Fourier transform infrared spectroscopy, thermogravimetric (TG), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analyses in this study. Microwave temperature (100 °C-200 °C), reaction time (30 min-90 min), and acid concentration (0.5 M-1.5 M) were the main influencing factors. Results of ultimate analysis indicated that the properties of the pretreated samples are better than those of the raw BS. Moreover, appropriately reducing the oxygen and ash contents and increasing the microwave temperature promoted decarboxylation and dehydration during pretreatment. Microwave-assisted acid pretreatment decreased the acetyl groups and hydrogen bonds. Of the three main influencing factors affecting the structure of moso BS, microwave temperature was the most important. TG analysis results indicated that the thermostability of the pretreated samples is improved after pretreatment. Moreover, the pyrolysis behavior of moso BS is insensitive to the reaction time and acid concentration under mild conditions. The relative contents of acids, furans, aldehydes, and ketones derived from the pretreated samples decreased according to the results of Py-GC/MS. Meanwhile, the relative glucopyranose and phenol contents of the pretreated samples are higher than those of the raw moso BS and achieve the maximum values of 48.31% and 20.18%, respectively, at 200 °C.