Pyrolysis characteristics and kinetics of typical seafood wastes

Pyrolysis is an important technology for the harmless reduction of food waste. In this paper, thermogravimetric analysis was used to analyze the pyrolysis characteristics of three typical seafood wastes, namely fish bones, crab shells, and shrimp shells, and to study the characteristic parameters of the pyrolysis process at different heating rates (20, 40, and 60 ℃/min), to analyze the effect of different components on the pyrolysis characteristics of seafood waste. The kinetic analysis of the pyrolysis process was carried out based on the pyrolysis characteristic parameters, combined with the apparent kinetic parameters and the fitting effects of various mechanism models were compared, and a more suitable mechanism model for the pyrolysis process of seafood waste was determined. The results showed that the pyrolysis processes of the three seafood wastes were closely related to their components, and the comparative analysis of TG-DTG curves found that the content of organic matter and inorganic salts were important factors affecting the pyrolysis process. The pyrolysis characteristic parameters of the three seafood wastes showed a consistent increasing trend with the increase of the heating rate. The main pyrolysis process of fish bones conforms to the first-order chemical reaction mechanism, and the organic matter decomposition stage of crab shells and shrimp shells can be described by a 1.5-order chemical reaction process. The large amount of chitin in shrimp shells and crab shells is the main reason for the difference in the order of chemical reactions. The activation energy increases with the increase of the heating rate, while the increment of the activation energy gradually decreases. It could be presumed that the adoption of larger heating rates over 40 ℃/min would probably not arise more severe pyrolysis condition, which would be more economical from technical view. The results achieved in this paper may provide some fundamentals for competitive technology development for seafood wastes pyrolysis and carbonization.