Pyrolysis of sargassum in a single mode microwave cavity: use of SiC and biochar as microwave absorbers

Abstract

This paper examines the feasibility of pyrolyzing the macroalgae sargassum, in a single-mode microwave cavity. Sargassum permittivities were measured and demonstrate the necessity of using a microwave absorber to help in reaching efficient pyrolysis. Silicon carbide, which is commonly used, and sargassum biochar, which has never been used before as a microwave absorber, were added to the system and their efficiencies were compared. Based on our experimental results, the high permittivity of sargassum biochar makes it a good microwave absorber. In comparison to the silicon carbide derived bio-oil, the sargassum biochar-derived bio-oil is of higher quality due to its lower acidity. Both microwave absorbers produce H₂ and CO rich biogas, but the biogas production is higher when biochar is used as an absorber. A complete analysis of the bio-oil components was done and confirms the less acidic character of the oil produced using biochar and the higher proportion of oxidized compounds produced with SiC.