Process time variation and critical growth onset analysis for nanofoam formation in sucrose-based hydrothermal carbonization

The paper presents a systematic study of the formation of carbon nanofoam from sucrose by hydrothermal carbonization. It is shown that for the process temperature of 150 °C, carbonization is not a gradual process but rather occurs suddenly at a specific threshold time of 4.5 h. pH value and electric...

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Bibliographic Details
Published in:Journal of materials science 2021-09, Vol.56 (27), p.15004-15011
Main Authors: Brooks, Carrie, Lee, Julia, Frese, Natalie, Ohtaki, Kenta, Wortmann, Martin, Sattler, Klaus
Format: Article
Language:English
Subjects:
Analysis
Carbon
Carbonization
Characterization and Evaluation of Materials
Chemical Routes to Materials
Chemistry and Materials Science
Classical Mechanics
Crystallography and Scattering Methods
Density
Electric properties
Electrical conductivity
Electrical resistivity
Materials Science
Morphology
Polymer Sciences
Solid Mechanics
Sucrose
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Summary:The paper presents a systematic study of the formation of carbon nanofoam from sucrose by hydrothermal carbonization. It is shown that for the process temperature of 150 °C, carbonization is not a gradual process but rather occurs suddenly at a specific threshold time of 4.5 h. pH value and electrical conductivity (EC) of the sucrose solution were monitored during carbonization. In the first 4.5 h prior to carbonization, the sucrose solution shows a sharp drop from pH 7.8 to pH 2 and sharp increase of EC. From this point on the values of pH and EC remain approximately constant. After the 4.5 h threshold, we examined the evolution of mass yield, density and morphology of the resulting carbon nanofoam. The yield first shows a steep increase around 4.5 h and then a further gradual increase up to 38% at 54.6 h. The mass density just after the 4.5 h threshold is 0.28 g/cm 3 and decreases with process time to reach a constant value of 0.14 g/cm 3 , between 20 and 54.6 h. This shows that desired conditions, such as low density and high yield, are obtained with sufficient process time below 5 h. Due to the release of intermediates of the conversion reaction into the sucrose solution, both pH and EC were found to be excellent indicators for the progression of hydrothermal carbonization.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-021-06222-4