title: Acceleration of Biochar Surface Oxidation during Composting?
abstract: Biochar composting experiments were performed to determine whether composting is a suitable method to accelerate biochar surface oxidation for increasing its reactivity. To assess the results, surface properties of Terra Preta (Brazil) and ancient charcoal pit (Northern Italy) biochars were additionally investigated. Calculation of O/C ratios by energy-dispersive X-ray spectroscopy demonstrated the anticipated increasing values from fresh biochars (0.13) to composted biochars (0.40), and finally charcoal pit biochars (0.54) and ancient Terra Preta biochars (0.64). By means of Fourier transformation infrared microscopy, formation of carboxylic and phenolic groups on biochars surface could be detected. Carboxylic acids of three composted biochars increased up to 14%, whereas one composted biochar showed a 21% lower proportion of carboxylic acids compared to the corresponding fresh biochar. Phenolic groups increased by 23% for the last mentioned biochar, and on all other biochars phenolic groups decreased up to 22%. Results showed that biochar surface oxidation can be accelerated through composting but still far away from ancient biochars.
authors: †Soil Biogeochemistry, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle, Germany.
authors: Katja
authors: K
authors: Wiedner
authors: †Soil Biogeochemistry, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle, Germany.
authors: Daniel
authors: D
authors: Fischer
authors: Sabine
authors: S
authors: Walther
authors: §Foxlab-Fondazione Edmund Mach, Via Mach 1, San Michele all'Adige, Trentoe 38010, Italy.
authors: Irene
authors: I
authors: Criscuoli
authors: ∥EURAC Research-Institute for Regional Development and Location Management, Viale Druso 1, Bolzano 39100, Italy.
authors: Filippo
authors: F
authors: Favilli
authors: ⊥Dendrochronologisches Labor, Landesamt für Denkmalpflege Baden-Württemberg, Regierungspräsidium Stuttgart, Fischersteig 9, 78343 Hemmenhofen, Germany.
authors: Oliver
authors: O
authors: Nelle
authors: †Soil Biogeochemistry, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120 Halle, Germany.
authors: Bruno
authors: B
authors: Glaser
mesh_terms: D002606:Charcoal / Q000737:chemistry*; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D012987:Soil; C540010:biochar; D002606:Charcoal
keywords: Terra Preta; biochar; composting; fourier transformation infrared microscopy; scanning electron microscopy; surface functional groups; surface oxidation