Sargassum is undoubtedly one of the most predominant brown macroalgae, posing a significant disposal problem for coastal areas worldwide. The effective valorization of Sargassum sp. would be beneficial not only for environmental mitigation but also for producing high-value chemicals. However, the valorization of Sargassum sp. for
bio-oil and
biochar production via slow pyrolysis has not been well studied yet. Hence, this study aimed to conduct a comprehensive investigation into
bio-oil and
biochar production from Sargassum sp. via slow pyrolysis to provide valuable data for further valorization. A batch reactor was employed, and the pyrolysis of Sargassum sp. was conducted in a temperature range of 400-600 °C and with retention times of 10-50 min. The results showed significant compounds could be identified in
bio-oil from Sargassum sp., including
carboxylic acids,
furan derivatives, aliphatic
hydrocarbons, and N-aromatic compounds. Based on the ultimate analysis, the H/C and O/C atomic ratios of
biochar were lower than the feedstock, reflecting the occurrence of
dehydration and decarboxylation reactions throughout the pyrolysis.
Biochar exhibited calorific values in the range of 23.12-25.89 MJ kg-1, indicating it has more potential to be used as a solid fuel than low-ranked
coals. Surface morphological analysis was performed by scanning electron microscopy (SEM) and showed a larger surface area in
biochar than in the algal feedstock. Furthermore, a reaction model was deduced, and it was confirmed that the pyrolysis reaction obeyed the Arrhenius behaviour. Overall, the slow pyrolysis of Sargassum sp. provides an opportunity to obtain value-added chemicals and biochars, which could be further utilized for other applications.