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Fractionation and identification of organic nitrogen species from bio-oil produced by fast pyrolysis of sewage sludge

Cao, Jing-Pei, Zhao, Xiao-Yan, Morishita, Kayoko, Wei, Xian-Yong, Takarada, Takayuki
Bioresource technology 2010 v.101 no.19 pp. 7648-7652
fatty acids, gases, fractionation, nitrogen, sewage sludge, lactams, decarboxylation, solvents, aromatic acids, pyrolysis, silica gel, mass spectrometry, gas chromatography, furnaces
Pyrolysis of sewage sludge was performed at 500°C and a sweeping gas flow rate of 300cm³/min in a drop tube furnace. Liquid fraction (i.e., bio-oil) from the sewage sludge pyrolysis was separated by silica-gel column chromatography (SGCC) with different solvents, including mixed solvents, as eluants. A series of alkanenitriles (C₁₃-C₁₈), oleamide, alkenenitrile, fatty acid amides and aromatic nitrogen species were fractionated from the bio-oil by SGCC and analyzed with a gas chromatography/mass spectrometry (GC/MS). Most of the GC/MS-detectable organic nitrogen species (ONSs) are lactams, amides and N-heterocyclic compounds, among which acetamide is the most abundant. N-heterocyclics with 1-3 rings, including pyrrole, pyridine, indole, benzoimidazole, carbazole, norharman and harman, were observed. The lactams detected include pyrrolidin-2-one, succinimide, phathalimide, glutarimide, piperidin-2-one and 3-isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione, all of which should be formed via decarboxylation and cyclization of γ- and δ-amino acids. Such a procedure provides an effective approach to fractionation and identification of ONSs from bio-oil produced by fast pyrolysis of sewage sludge.