Surface Properties and Chemical Composition of Corncob and Miscanthus Biochars: Effects of Production Temperature and Method

Biochar properties vary, and characterization of biochars is necessary for assessing their potential to sequester carbon and improve soil functions. This study aimed at assessing key surface properties of agronomic relevance for products from slow pyrolysis at 250–800 °C, hydrothermal carbonization...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2014-04, Vol.62 (17), p.3791-3799
Main Authors: Budai, Alice, Wang, Liang, Gronli, Morten, Strand, Line Tau, Antal, Michael J, Abiven, Samuel, Dieguez-Alonso, Alba, Anca-Couce, Andres, Rasse, Daniel P
Format: Article
Language:English
Subjects:
biochar
carbon
cation exchange capacity
Charcoal - chemistry
chemical composition
corn cobs
feedstocks
Hydrogen-Ion Concentration
hydrothermal carbonization
Miscanthus
pyrolysis
surface area
Surface Properties
Temperature
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Summary:Biochar properties vary, and characterization of biochars is necessary for assessing their potential to sequester carbon and improve soil functions. This study aimed at assessing key surface properties of agronomic relevance for products from slow pyrolysis at 250–800 °C, hydrothermal carbonization (HTC), and flash carbonization. The study further aimed at relating surface properties to current characterization indicators. The results suggest that biochar chemical composition can be inferred from volatile matter (VM) and is consistent for corncob and miscanthus feedstocks and for the three tested production methods. High surface area was reached within a narrow temperature range around 600 °C, whereas cation exchange capacity (CEC) peaked at lower temperatures. CEC and pH values of HTC chars differed from those of slow pyrolysis biochars. Neither CEC nor surface area correlated well with VM or atomic ratios. These results suggest that VM and atomic ratios H/C and O/C are good indicators of the degree of carbonization but poor predictors of the agronomic properties of biochar.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf501139f