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2017
Journal Article
Titel
Source and biological response of biochar organic compounds released into water; relationships with bio-oil composition and carbonization degree
Abstract
Water-soluble organic compounds (WSOCs) were extracted from corn stalk biochar produced at increasing pyrolysis temperatures (350-650 °C) and from the corresponding vapors, collected as bio-oil. WSOCs were characterized by gas chromatography (semivolatile fraction), negative electron spray ionization high resolution mass spectrometry (hydrophilic fraction) and fluorescence spectroscopy. The pattern of semivolatile WSOCs in bio-oil was dominated by aromatic products from lignocellulose, while in biochar was featured by saturated carboxylic acids from hemi/cellulose and lipids with concentrations decreasing with decreasing H/C ratios. Hydrophilic species in poorly carbonized biochar resembled those in bio-oil, but the increasing charring intensity caused a marked reduction in the molecular complexity and degree of aromaticity. Differences in the fluorescence spectra were attributed to the predominance of fulvic acid-like structures in biochar and lignin-like moieties in bio-oil. The divergence between pyrolysis vapors and biochar in the distribution of WSOCs with increasing carbonization was explained by the hydrophobic carbonaceous matrix acting like a filter favoring the release into water of carboxylic and fulvic acid-like components. The formation of these structures was confirmed in biochar produced by pilot plant pyrolysis units. Biochar affected differently shoot and root length of cress seedlings in germination tests highlighting its complex role on plant growth.
Author(s)
Ghidotti, Michele
Interdepartmental Centre for Industrial Research Energy and Environment, CIRSA, University of Bologna, via S. Alberto 163, Ravenna, Italy
Fabbri, Daniele
Interdepartmental Centre for Industrial Research Energy and Environment, CIRSA, University of Bologna, via S. Alberto 163, Ravenna, Italy
Masek, Ondrej
UK Biochar Research Centre, School of GeoSciences, University of Edinburgh, Crew Building, Alexander Crum Brown Road, Edinburgh, United Kingdom
Mackay, Logan Colin
SIRCAMS, School of Chemistry, University of Edinburgh, Joseph Black Building, King's Buildings, West Mains Road, Edinburgh, United Kingdom
Montalti, Marco
Department of Chemistry ""G. Ciamician"", University of Bologna, Via Selmi 2, Bologna, Italy