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

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. This paper examines the feasibility of pyrolyzing the macroalgae sargassum, in a single-mode microwave cavity using char or SiC as microwave absorber.