Conversion of sweet potato waste to solid fuel via hydrothermal carbonization

• Published in: Bioresource technology 2018-02, Vol.249, p.900-907
• Main Authors: Chen, Xinfei, Ma, Xiaoqian, Peng, Xiaowei, Lin, Yousheng, Yao, Zhongliang
• Format: Article
• Language: English
• Subjects: Biofuels; Carbon; Chemical composition; Hot Temperature; Hydrochars; Hydrothermal carbonization; Ipomoea batatas; Kinetics; Sweet potato waste; Temperature; Thermogravimetry
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2017.10.096

•Hydrothermal carbonization of sweet potato waste was developed.•The effects of HTC temperature and time on hydrochars properties were investigated.•The HHV and energy densification of hydrochars were improved.•The combustion characteristic of the hydrochars was upgraded. Hydrothermal carbonization (HTC) of sweet potato waste was performed to investigate the effect of process parameters including reaction temperature (180–300 °C) and residence time (0–120 min) on the characteristics of hydrochars. The results showed that the increase of reaction temperature and residence time both decreased the yield of hydrochars. With the increase of reaction temperature and residence time, the carbon content of hydrochars increased, while the hydrogen and oxygen contents decreased. The lower H/C and O/C ratios indicated that dehydration and decarboxylation reactions occurred during HTC. The occurrence of aromatization reaction was found in FTIR spectra. Thus, the fixed carbon content, higher heating value, and energy density of hydrochars increased. SEM analysis indicated that HTC developed rough surface with crack on the hydrochars. The thermogravimetric experiments displayed the increase trend in combustion ignition temperature, burnout temperature and activation energy as reaction temperature and time increase, which showed better combustion characteristics.