Distributions of organic compounds to the products from hydrothermal liquefaction of microalgae

In this study, the analysis of organic compounds in the products obtained from hydrothermal liquefaction (HTL) of microalgae (Dunaliella tertiolecta) was carried out, with particular attention on the identification of compounds in aqueous phases via the integration of two pre-treatment methods namely dried aqueous extracts (DAE) and solid-phase micro-extraction (SPME) along with GC-MS analysis. The results showed that the strong polar compounds in aqueous phases, such as carboxylic acids, alcohols, amides, glycerol, and N-containing compounds were determined through DAE method. The weak polar compounds like phenols, cyclic hydrocarbons, and indoles were identified via SPME method. In addition, CO2 and CO are the main components of the gaseous phase products, the rest of components include CH4, N2, H2, C2H4, C2H6, etc. Bio-oil is mainly composed of ketones, phenols, alcohols, hydrocarbons and N-containing compounds. Based on the compounds in the bio-oil, aqueous and gaseous phases compared with the other previous published works, the plausible pathways of Dunaliella tertiolecta HTL are proposed. © 2016 American Institute of Chemical Engineers Environ Prog, 2016