Biochar from brown algae: Production, activation, and characterisation

Biochar has shown promise in combining water treatment and soil enhancement with long term carbon sequestration. Biochar performance depends on the feedstock and the pyrolysis process conditions. In this study, we conducted biochar production, activation, and characterisation from the brown algae Laminaria digitata, Saccharina latissima, Saccorhiza polyschides, Himanthalia elongata, and pelagic sargassum for several potential applications. Our results showed that these seaweeds, as harvested and without washing, contained significant amount of salt that needs to be removed to improve biochar quality for application in water treatment. However, presence of salts may confer advantages in certain catalytic processes. X-ray computed micro-tomography analysis shows the formation of porosity as a result of pyrolysis and biochar activation. Chemical activation successfully improved the biochar quality, in particular the available surface area for water and soil remediation. These results pave the way to extend applications of brown algae derived activated biochars.