Bioenergy from Food Wastes: Thermal Decomposition of Carbohydrates, Lipids, and Proteins

Abstract

Abstract. Food wastes differ in composition based on their sources and hence are difficult to use in gasification and pyrolysis technologies. The objectives of this study were to investigate the thermal devolatilization kinetics and pyrolysis products of three representative food components: lipids, carbohydrates, and protein. Devolatilization of carbohydrates and proteins occurred up to 600°C with a total weight loss of 90%. In particular, dextrose, sucrose, histidine, and phenylalanine exhibited a combined two-reaction decomposition scheme, whereas starch and valine exhibited a single-reaction scheme. Sucrose had a higher activation energy than dextrose as more energy was needed to cleave glyosidic linkages. Valine had the lowest activation energy (70.2 kJ mol-1) of all the protein model compounds due to its simple structure. However, the lipids primarily vaporized below 400°C and did not decompose. Pyrolysis products of carbohydrates were largely composed of furan and sugar-based compounds, whereas those of proteins varied depending on the type of protein. Because lipids mainly vaporized, only slight conversion (<1%) into different lipid types and hydrocarbons was observed. Keywords: Carbohydrate, Devolatilization, Food waste, Lipid, Protein, Py-GC/MS, Pyrolysis, Reaction kinetics, TGA.