TY - JOUR
T1 - Hydrothermal carbonization of sludge
T2 - Effect of steam release on products properties and wall sticking phenomenon
AU - Xiao, Yao
AU - Ding, Lu
AU - Leghari, Asma
AU - Yu, Mengyan
AU - Gao, Ming
AU - Yang, Yu
AU - Gao, Yunfei
AU - Chen, Wei Hsin
AU - Chen, Xueli
AU - Wang, Fuchen
N1 - Funding Information:
This work was supported by the project of the National Key Research and development (R&D) Program and International Science and Technology Innovation Project between Governments (2021YFE0108900), Belt & Road Young Scientist Exchange Project Supported by Fund of Shanghai Science and Technology Committee (20230742400), and Pujiang Talent Program Supported by Fund of Shanghai Science and Technology Committee (20PJ1402800).
Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/5/1
Y1 - 2023/5/1
N2 - In order to understand hydrothermal carbonization (HTC) process more effectively, the effect of steam-release process at different temperatures (160, 180, 200, and 220 °C) on product properties and wall sticking phenomenon were studied. Experimental results indicated that the approximate equilibrium moisture content (AEMC) of hydrochar obtained with (SRHC) and without (HC) steam-release process were both negatively correlated with zeta potential (R = −0.96326 for HC and R = −0.95825 for SRHC). More importantly, the absolute value of the zeta potential of SRHC was lower than HC indicating steam-release process significantly improve dewatering performance of sludge after HTC treatment. The results of FE-SEM and N2 adsorption–desorption experiments indicated steam-release process was favorable for the formation of porous hydrochar. The variation of surface functional groups showed that the intensity of all peaks in SRHC was significantly lower than HC, indicating steam-release process which significantly affects surface chemical properties of samples. As for liquid, TOC, TN and COD value of the condensate were lower than filtrate, indicating steam-release process which produces “cleaner” condensed liquid with less organic matter content. The wall sticking phenomenon in the steam-release process became more severe with increasing temperature and the amount of sticky wall sample (SWS) increased from 0.392 g at 160 °C to 2.131 g at 220 °C, which indicated that temperature was key factor affecting the sticking phenomenon on the inside wall of the reactor. The contact angle of SWS and SRHC decreased from 60.083° and 77.283° at 160 °C to 51.317° and 67.967° at 220 °C, and the polar free energy of SWS (12.52–14.00 mN/m) was significantly higher than that of SRHC (1.85–4.53 mN/m), indicating increasing hydrophobicity and reducing polar free energy of sample were key factors in improving sticking phenomenon.
AB - In order to understand hydrothermal carbonization (HTC) process more effectively, the effect of steam-release process at different temperatures (160, 180, 200, and 220 °C) on product properties and wall sticking phenomenon were studied. Experimental results indicated that the approximate equilibrium moisture content (AEMC) of hydrochar obtained with (SRHC) and without (HC) steam-release process were both negatively correlated with zeta potential (R = −0.96326 for HC and R = −0.95825 for SRHC). More importantly, the absolute value of the zeta potential of SRHC was lower than HC indicating steam-release process significantly improve dewatering performance of sludge after HTC treatment. The results of FE-SEM and N2 adsorption–desorption experiments indicated steam-release process was favorable for the formation of porous hydrochar. The variation of surface functional groups showed that the intensity of all peaks in SRHC was significantly lower than HC, indicating steam-release process which significantly affects surface chemical properties of samples. As for liquid, TOC, TN and COD value of the condensate were lower than filtrate, indicating steam-release process which produces “cleaner” condensed liquid with less organic matter content. The wall sticking phenomenon in the steam-release process became more severe with increasing temperature and the amount of sticky wall sample (SWS) increased from 0.392 g at 160 °C to 2.131 g at 220 °C, which indicated that temperature was key factor affecting the sticking phenomenon on the inside wall of the reactor. The contact angle of SWS and SRHC decreased from 60.083° and 77.283° at 160 °C to 51.317° and 67.967° at 220 °C, and the polar free energy of SWS (12.52–14.00 mN/m) was significantly higher than that of SRHC (1.85–4.53 mN/m), indicating increasing hydrophobicity and reducing polar free energy of sample were key factors in improving sticking phenomenon.
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U2 - 10.1016/j.fuel.2023.127486
DO - 10.1016/j.fuel.2023.127486
M3 - Article
AN - SCOPUS:85147104987
SN - 0016-2361
VL - 339
JO - Fuel
JF - Fuel
M1 - 127486
ER -