Hydrothermal Reactions of Biomolecules Relevant for Microalgae Liquefaction

Abstract

Hydrothermal liquefaction (HTL) of microalgae, a process that uses water at high temperature and high pressure to make a renewable crude bio-oil, is receiving increased attention. Understanding the governing reaction pathways for the biomolecules in the microalgae cell could lead to improved conversion processes. This review collects information pertinent to the behavior of microalgae biomolecules (e.g., proteins, polysaccharides, lipids, chlorophyll) and their hydrothermal decomposition products (e.g., amino acids, sugars, fatty acids) in high temperature water (HTW). We report on studies involving individual compounds and their mixtures. The mixture systems are particularly important as they move closer to mimicking the true chemistry of HTL of microalgae by providing opportunities for interactions between different molecules that would be present during HTL. Throughout this review, we highlight gaps in the understanding of different chemical reactions that may take place during HTL of microalgae.

Decomposition of Amino Acids in Water with Application to In-Situ Measurements of Enceladus, Europa and Other Hydrothermally Active Icy Ocean Worlds

“…The decomposition of amino acids in water has been extensively studied for its applications to organic geochemistry (e.g. Ito et al, 2006Ito et al, , 2009, extracting and recycling proteinaceous products in industry or biotechnology (e.g., Zhu et al, 2011, Changi et al, 2015 and in investigations of the hydrothermal origin of life (e.g. Bada et al, 1995).…”

Hydrothermal liquefaction of oil mill wastewater for bio-oil production in subcritical conditions

“…Most of saturated fatty acids were C 16 compounds which reacted before C 18 compounds (Watanabe , et al, 2006). Hydrolysis of protein in subcritical water are well studied (Changi, et al, 2015). In fact, protein breaks down into amino acids which explains their presence in WSP.…”

Catalytic hydrothermal liquefaction of Spirulina platensis : Focusing on aqueous phase characterization

“…Besides, the pH of the aqueous slurry was reported as a critical factor to amino acid conversion. The acidic condition would prevent the conversion of amino acids like methionine and arginine while favoring the conversion of leucine and serine . Sakata et al reported the enhancement of the oligomerization pathways to form the dimer of glycine under the alkaline environment.…”