Correlation between solubility parameters and recovery of phenolic compounds from fast pyrolysis bio-oil by diesel extraction

Fast pyrolysis bio-oils (fpBO) were extracted with two alternative commercial transportation fuels, hydrocarbon diesel and bio-diesel. The extraction of fpBO with commercial diesel fuel provided a yield of 4.3 wt%, but the yield increased significantly to 26.6 wt% when bio-diesel was the extractant. The molecular weight of fpBO before and after extraction were consistent with the loss of a more soluble, low molecular weight fraction from the crude fpBO. The relative energy difference (RED), based on the Hansen solubility parameter (HSP), is used to examine the extraction efficiency of specific compounds in the two different ???solvents???. Differences in the RED values could be used to rationalize differences in the partitioning of common fpBO phenolics.