506 / 2018-09-13 08:39:22

Evaluation of the Effects of Cooking Treatment on the Pyrolysis of Shrimp Shell Samples

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Shrimp shells are composed of organic complexes containing high-calcium and high-nitrogen. Compared with the techniques of extracting chitin from shrimp shells, low-temperature pyrolysis is a promising method to reduce the environmental pollution of shrimp shells waste and improve the full-scale resource utilization rate. However, the distribution and the characteristics of pyrolysis products from shrimp shells were strongly determined by the interactions between the volatiles and semi-coke. And cooking pretreatment changed the properties of shrimp shells to make the pyrolysis process more complicated. The focus of this study is to explore the pyrolysis mechanism of both raw and cooked shrimp shells based on the illumination of the interactions among volatiles as well as the reactions between volatiles and semi-coke. Among the pyrolysis products of raw shrimp shells, char accounted for more than 60%, tar occupied about 20%, and the least was pyrolysis gas. The increasing of the temperature from 400oC to 600oC stimulated the decomposition of char (CaCO3 and carbon residue) and/or tar (pyridine, cyanobenzene and acetamide derivatives) to produce more gases (CO2, H2 and CH4). After cooking treatment, the fraction of the organic components increased in the shrimp shells and became more easily cracked, thus more tar and gases were produced under the same pyrolysis conditions. Nevertheless, the same trend for both samples was found that the interactions among various volatiles affected the type and location of substituents of the same derivatives. Interestingly, the organic carbon remaining in the interactions caused the CaCO3 in the cooked shrimp shells to exhibit more easily decomposed characteristics.