Stable diesel and bio-oil emulsion through solvent extraction and ultrasonic aided emulsification

Fast pyrolysis bio-oil is considered a highly preferable supplement to conventional fossil fuels. However, the direct application of pyrolysis bio-oil is limited due to poor fuel properties. Emulsification of bio-oil with diesel using a solvent is considered a relatively straightforward technique for utilizing bio-oil directly with diesel. In this study, new solvents were studied with the aid of sonication to produce a stable emulsion of diesel and bio-oil. 2-Octanol, 2-Heptanol and 2-Octanone were selected as solvents based on computer-aided molecular design (CAMD) method. Bio-oil was blended with 5, 10, 15 and 20 wt% of 2-Octanol using sonication. The solvent-oil blends with different solvents (2-Heptanol and 2-Octanone) at 20 wt% were also investigated for extracting organics from bio-oil. Subsequently, sonication-assisted emulsification of the solvent-extracted bio-oil with diesel was conducted with the aid of a composite surfactant with a hydrophilic-lipophilic balance (HLB) value of 7. Extraction of bio-oil with 20 wt% of 2-Octanol provided a maximum organic yield of 37.9 +/- 1.3 % with a Higher Heating Value (HHV) of 31.9 MJ/kg. The desired ratio for emulsification was found to be 80: 15: 5 (diesel: surfactant: solvent-extracted bio-oil). The emulsion samples showed promising quality with an HHV of 44.0 MJ/ kg and a pH of 8.0 +/- 0.1. Moreover, no phase separation was observed even after the accelerated ageing process at 80 degrees C for 24 hours. The results showed that all three solvents had an overall positive effect on the extraction of organics from bio-oil and aided in emulsification with diesel in which 2-Octanol was the most effective solvent for achieving a stable diesel - bio-oil emulsion.