Application of Novel Pyrolysis Reactor Technology to Concentrate Bio-oil Components with Antioxidant Activity from Tobacco, Tomato and Coffee Ground Biomass

Abstract

To make biomass conversion to fuels more cost-effective, value-added products, including pharmaceuticals, should be produced from agricultural residues. The objectives of this study were (1) to investigate the antioxidant properties of bio-oil produced from the pyrolysis of biomass and (2) to concentrate and identify antioxidant compounds from the bio-oil. This study used a two stage mechanically fluidized reactor (MFR) where the first stage, termed one-dimensional (1-D), produces vapors with varying chemical composition based on the reactor temperature while the two-dimensional (2-D) stage, separates vapor components according to their condensation temperature. Tobacco leaf (Nicotiana tabacum), tomato plant (Solanum lycopersicum) and spent coffee (Coffea arabica) grounds (<1 mm) were pyrolyzed at a heating rate of 10 °C/min from ambient to 565 °C. The 400–565 °C reactor temperature cuts of all three biomass bio-oils from 1-D MFR pyrolysis produced the highest amount of antioxidant activity compared to the other bio-oil cuts and the 2-D MFR pyrolysis of tomato plant bio-oil collected in the 120 °C condenser had the highest concentration of antioxidants. The 50% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging potential (IC50 value) of the reference compound ascorbic acid and tomato bio-oil cut collected in the 120 °C condenser was 138 µg/mL versus 37 mg/mL, respectively. The gas chromatography–mass spectrometry (GC–MS) analysis identified 2-furanmethanol, phenol and glucose in the tomato bio-oil. The findings indicate the two stage MFR process can be used to concentrate antioxidants during bio-oil production by reactor and condenser temperature controls thus providing a useful tool for producing value-added compounds while processing agricultural residues.