Polarity-based separation and chemical characterization of fast pyrolysis bio-oil from poultry litter

• PL oil was separated into four fractions using polarity-based fractionation method.
• The methanol fraction is a major cause of the high viscosity of the PL oil.
• Fatty acids were predominant components of the hexane and toluene fractions.
• The major component in methanol fraction was 1, 6-anhydro-glucose.

140 g Poultry litter pyrolysis oils (PL oils) were separated into four fractions using polarity based fractionation method. Four solvents of increasing polarity (hexane < toluene < chloroform < methanol) were used to sequentially fractionate the PL oil into four fractions (hexane fraction, toluene fraction, chloroform fraction and methanol fraction). The mass of hexane, toluene, chloroform and methanol fractions was 46 g, 29 g, 48 g and 14 g, respectively. The hexane and toluene fractions had low viscosity, while chloroform fraction was viscous and methanol fraction was almost solid at ambient laboratory conditions. The four PL oil fractions were characterized using Fourier Transform Infrared (FT-IR) spectrometry, 13C Nuclear Magnetic Resonance (NMR) spectrometry, and their organic elemental composition and higher heating values were also determined. Furthermore, major compounds in the four fractions were isolated by column chromatography. As a result, four compound classes (fatty acids, sterols, phenols and carbohydrates) and eleven major compounds were isolated from these four fractions. Oleic acid was predominant component of the hexane fraction (48.6%). The major component in methanol fraction was 1, 6-anhydro-β-D-glucose (16.7%), but the chloroform fraction had no predominant component. The 1, 6-anhydro-β-D-glucose and other sugar derivatives were water soluble and were selectively removed from the PL oil by water extraction and this subsequently decreased the viscosity of residual PL oil.