Aaron E. Brown1, Jessica M. M. Adams2 and Andrew B. Ross1
1 School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK, 2 Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth SY23 3EB, UK
Brown macroalgae offer a large potential source of biomass for the generation of sustainable energy, platform chemicals and bioactive compounds. However, the scale-up of this industry is dependent on identifying suitable technologies which can effectively process macroalgal biomass to facilitate extraction of target compounds or conversion into a suitable energy vectors. Subcritical water processing has been identified as a rapid and environmentally-friendly hydrothermal conversion technology which involves the conversion of biomass in hot compressed liquid water. Higher-end hydrothermal processing temperatures (150-250°C), termed Hydrothermal Carbonisation (HTC), facilitates the conversion of macroalgae to energy vectors. Alternatively, less-severe hydrothermal processing (100-180°C) can be utilised as a method of extracting high-value compounds from macroalgae, such as fucoidan. However, varying the reaction severity influences both the yield and characteristics of fucoidan extracts: influencing downstream applications. This aim of this study is to investigate how the yields and properties of fucoidan extracts vary according to different hydrothermal reaction severities. Extractions were conducted for three species of Fucales: Fucus serratus, Fucus vesiculosus, Ascophyllum nodosum, using a 45mL Parr reactor across a range of temperatures (100-180°C), retention times (5-15 min) and solid loading ratios (0.05-0.1 g mL-1). The effect of process severity on fucoidan yields and properties will be discussed, alongside the potential opportunities for energy valorisation of process residues.