Polyols obtained from solvolysis liquefaction of biodiesel production solid residues

In this study, the possibilities of solvolysis liquefaction of the main solid residue generated in the rapeseed biodiesel production process into a liquid form were investigated by using polyhydric alcohols [polyethylene glycol (PEG #400) and glycerol] and their ensuing polyols obtained were evaluated. The influences of some liquefaction parameters on the residue content, such as mass/solvent ratio, liquefaction temperature and time, were discussed. The results show that the biopolyols production from rapeseed cake residue under different liquefaction conditions is completely feasible. The Fourier transform-infrared (FT-IR) of the liquefied product showed that cellulose, hemicellulose and lignin are almost decomposed in the liquefaction reaction. To open new avenues of exploitation of liquefied product, several physical and chemical characteristics of polyols were determined and the detailed chemical compositional analysis was performed by gas chromatography–mass spectrometry (GC–MS). The GC–MS analysis showed that the chemical components can be divided into several groups, i.e., glycols, acids, ester and ether compounds. The OH number and viscosity in the polyol were 505 mg of KOH/g and 0.4 Pa s, respectively; being values found in the range of those current petroleum-based polyols used as precursor in polyurethane synthesis.

► Liquefaction of the residue generated in the rapeseed biodiesel production process.
► Characterization of resultant polyols under different reaction conditions
► Optimal conditions for liquefaction of rapeseed cake residue.
► Obtained polyols could be used as precursor in polyurethane synthesis.