Soil Research Soil Research Society
Soil, land care and environmental research

Chemical and structural properties of carbonaceous products obtained by pyrolysis and hydrothermal carbonisation of corn stover

A. B. Fuertes A , M. Camps Arbestain B F , M. Sevilla A , J. A. Maciá-Agulló A , S. Fiol C , R. López C , R. J. Smernik D , W. P. Aitkenhead B , F. Arce C and F. Macias E

A Instituto Nacional del Carbón (CSIC), Apartado 73, 33080-Oviedo, Spain.

B New Zealand Biochar Research Centre, Private Bag 11222, Massey University, Palmerston North 4442, New Zealand.

C Departamento de Química Física, Facultad de Química, Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain.

D School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, Urrbrae, SA 5064, Australia.

E Departamento de Edafología y Química Agrícola, Facultad de Biología, Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain.

F Corresponding author. Email:

Australian Journal of Soil Research 48(7) 618-626
Submitted: 5 January 2010  Accepted: 10 May 2010   Published: 28 September 2010


The main properties of chars produced from corn stover, either by pyrolysis at 550°C (to produce biochar) or by hydrothermal carbonisation (to produce hydrochar), were studied. Carbonaceous materials were characterised by: SEM imaging, solid-state 13C NMR, FT-IR, Raman spectroscopy, and XPS. The following parameters were determined: elemental composition, cation exchange capacity, acid groups contents, BET, and yield. The hydrochar had a low ash content and low pH (4.7); recovery of C was high (57%), although only about half of the C was aromatic. Atomic O/C and H/C ratios in the hydrochar were higher than in the biochar. The same pattern was observed for the estimated concentration of carboxylic functional groups (0.07 compared with 0.04 mol/kg). The biochar had higher ash content than the hydrochar, and also higher pH (~10) (lime equivalence ~40 kg CaCO3/t). The C recovery (46%) was lower than in the hydrochar, although most of the C recovered was aromatic. Both chars could be used as soil amendments, for very different requirements. Soil responses and the residence times of the chars (especially the hydrochar) must be studied in detail to pursue long-term C sequestration.

Additional keywords: biochar, hydrochar, hydrothermal carbonisation, pyrolysis.


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