Physiochemical characterization of synthetic bio-oils produced from bio-mass: a sustainable source for construction bio-adhesives

This paper investigates physicochemical properties of four different types of bio-oil produced through hydrothermal liquefaction (HTL) and vacuum pyrolysis including wood pallet, corn stover, miscanthus and swine manure. It should be noted that the term bio-oil in this paper is used to refer to synthesized oil from post processing of biomass. Accordingly, swine manure was processed under HTL conditions of 340 degrees C, 10-12 MPa with 15 min residence time. Bio-oils from miscanthus, corn stover and wood pellet were produced at 450 degrees C under vacuum pyrolysis. Furthermore, in this paper the merit of applying each of these bio-oils as a precursor for producing bio-adhesive was studied using physiochemical and rheological characterization. Chemical functional groups and individual compounds were identified with GC-MS, NMR and FT-IR, while molecular weight distribution determined using GPC showed that wood pellet bio-oil has the lowest molecular weight followed by those from corn stover, miscanthus and swine manure. In addition, boiling point distributions of different fractions of bio-oils were analyzed. Furthermore, TLC-FID was used to determine different fractions of bio-oils based on their solubility in comparison with those of petroleum. It was shown that overall bio-oils from woody bio-mass have higher amount of alcoholic compounds as evidenced by the presence of strong peaks related to ether and alcohols in FTIR spectra; in addition, the TLC-FID analysis showed presence of higher fraction of fused poly aromatic rings referred to "asphaltene" in bio-oils produced from woody biomass compared to bio-oils from swine manure. The results of our characterization show the importance of feedstock composition and their effect on the characteristics of bio-oils as well as their applicability for use in bio-adhesives production.