NOVEL SOLVENT EXTRACTION PROCESSES FOR THE RECOVERY OF LIPIDS AND VALUE-ADDED COMPOUNDS FROM MICROALGAE FOR SUSTAINABLE BIOFUEL AND CHEMICAL PRODUCTION

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Abstract

Microalgae biomass is attracting increasing attention worldwide as a promising feedstock to develop multipurpose third generation biorefineries. Due to its ability to accumulate lipids for biofuel production, along their capacity to synthesize natural polyphenolic antioxidants for fine chemical and pharmaceutical applications, microalgae biomass is an excellent resource for production of bioenergy and high-value compounds. However, efficient downstream processes to recover target biomolecules from microalgae remains a major bottleneck. Conventional extraction techniques for biomolecule extraction from microalgae rely on the use of petroleum-derived volatile organic solvents, which are being increasingly restricted in the chemical industry due to their adverse effects on environment and human health. Consequently, cost-effective technologies to extract biomolecules using alternative solvents with a better environmental, health and safety profile are required. Therefore, the main objective of the present thesis project is to evaluate green solvents for extraction of lipids and polyphenols from microalgae for sustainable production of biodiesel and bioactive antioxidants. Microalgal lipid extraction was performed using a variety of bio-based solvents, while antioxidant recovery was accomplished using renewable deep eutectic solvents and compared against benchmark organic solvents. Lipid extraction performance was evaluated in terms of lipid extraction capacity, saponifiablity and biodiesel yield after transesterification; meanwhile, antioxidants recovery performance was assessed based on total phenolic content, antioxidant activity and polyphenolic profile of the extracts. Additionally, extraction solvent effects on biomass structure were assessed to enhance further bioprocessing steps. Lastly, the feasibility of different integrated strategies for co-production of biofuel and antioxidants from microalgae were explored to maximize the quantity and quality of the biorefinery output. Overall, this research project provides a comprehensive evaluation of advanced microalgal biorefineries for sustainable production of biofuel and valuable chemicals, contributing to promote strong bio-based industries for transitioning to bio-based economy.

Keyword(s)

bio-based solvents; biofuel; deep eutectic solvents; green solvents; lipids; polyphenolics

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