Characterization of Solid Residues Obtained from Supercritical Ethanol Liquefaction of Swine Manure

Animal wastes are considered as renewable energy resources, which contain a great energy potential. For this study, swine manure was treated with supercritical ethanol within the reaction temperature range of 240-360°C to produce bio-oil, resulting in a significant amount of solid residues. Solid residues were characterized by using Fourier Transform Infrared (FT-IR), Scanning Electron Microscopic (SEM), surface area, elemental and thermogravimetric (TG) analyses. Solid residues were mainly composed of carbon (26-29 wt%) and ash (35-45 wt%) and exhibited low surface areas (11-17 m²/g). The analyses indicated an incomplete conversion of lignocellulosic components and thermal chemical reactions including hydrolysis, dehydration, decarboxylation, aromatization and condensation. Supercritical ethanol liquefaction is considered as a feasible way to remove oxygen and utilize carbon and hydrogen in swine manure to produce carbonaceous materials and energy condensed bio-fuels.