The influence of feedstock and production temperature on biochar carbon chemistry: a solid-state 13C NMR study

McBeath, Anna V., Lehmann, Johannes, Krull, Evelyn S., and Smernik, Ronald J. (2014) The influence of feedstock and production temperature on biochar carbon chemistry: a solid-state 13C NMR study. Biomass & Bioenergy, 60. pp. 121-129.

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Abstract

Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy was used to evaluate the carbon chemistry of twenty-six biochars produced from eleven different feedstocks at production temperatures ranging from 350°C to 600°C. Carbon-13 NMR spectra were acquired using both cross-polarisation (CP) and direct polarisation (DP) techniques. Overall, the corresponding CP and DP spectra were similar, although aromaticity was slightly higher and observability much higher when DP was used. The relative size and purity of the aromatic ring structures (i.e. aromatic condensation) were also gauged using the ring current technique. Both aromaticity and aromatic condensation increased with increasing production temperature, regardless of the feedstock source. However, there were clear differences in these two measures for biochars produced at the same temperature but from different feedstocks. Based on a relationship previously established in a long-term incubation study between aromatic condensation and the mean residence time (MRT) of biochar, the MRT of the biochars was estimated to range from <260 years to >1400 years. This study demonstrates how the combination of feedstock composition and production temperature influences the composition of aromatic domains in biochars, which in turn is likely to be related to their recalcitrance and ultimately their carbon sequestration value.

Item ID: 36497
Item Type: Article (Research - C1)
ISSN: 1873-2909
Keywords: biochar; solid-state 13C NMR spectroscopy; aromatic condensation; mean residence time; carbon sequestration; pyrolysis
Funders: Australian Government's Climate Change Research Program, Grains Research and Development Corporation
Date Deposited: 05 Dec 2014 04:23
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050301 Carbon Sequestration Science @ 40%
03 CHEMICAL SCIENCES > 0306 Physical Chemistry (incl Structural) > 030606 Structural Chemistry and Spectroscopy @ 40%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0703 Crop and Pasture Production > 070304 Crop and Pasture Biomass and Bioproducts @ 20%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 50%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960302 Climate Change Mitigation Strategies @ 40%
96 ENVIRONMENT > 9614 Soils > 961402 Farmland, Arable Cropland and Permanent Cropland Soils @ 10%
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