Evaluation of bio-oil fractions from woody biomass pyrolysis as precursors for bio-binder in anode manufacture

To reduce the environmental impact of the aluminium industry, this study evaluates various bio-oil fractions as precursors to synthesize bio-binder, which is a potential sustainable alternative to coal tar pitch. Bio-oil fractions, including unfiltered and filtered bio-oils, and their aqueous and organic fractions, were investigated. The bio-oil and bio-binder samples were extensively characterized in terms of physicochemical properties and toxicological assessment. The evaluation demonstrates that the organic bio-oil fraction exhibits higher carbon content, greater aromaticity degree, and improved thermal stability. Toxicity assessment reveals that filtration effectively reduces the toxic risk associated with the bio-oil. The bio-binder derived from the organic fraction possesses a higher carbon content of 74.5 wt.%, a viscosity of 4.84 Pa·s, and superior thermal and oxidative stabilities, compared to other bio-oil fractions. The green anode made of filtered organic fraction shows comparable apparent density and electrical resistivity to that made of commercial binder. The findings suggest that the filtered bio-oil organic fraction is a promising precursor for bio-binder synthesis, with properties approaching those of coal tar pitch. This study introduces comprehensive perspectives and methodologies for selecting and tuning bio-oil as a sustainable alternative for the carbon anode production in the aluminium industry.