Green approaches and separation techniques for the recovery of pigments from microalgae

Khoo, Kuan Shiong (2021) Green approaches and separation techniques for the recovery of pigments from microalgae. PhD thesis, University of Nottingham.

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Microalgae have provided great exploitation of biofuels and bioproducts production over fossil fuels and other plant-based sources owing to its high accessibility, non-competition, and renewability advantages. The production of natural carotenoids from microalgae are safer than petrochemical feedstock due to the inherent toxicity concerns for direct human consumption. However, the recalcitrant structure of microalgae cell wall restricted the direct recovery and extraction of the carotenoids accumulated inside the biomass which requires an additional pretreatment process. The current conventional technologies (e.g. bead beating, homogenizers, high pressure heating and chemicals) of biomass processing are incompetent and not feasible for the downstream processing of microalgae. This creates an opportunity of developing novel bioprocessing approaches to reduce the overall cost- and time processing and enhance the efficient production of carotenoids.

This thesis presents the development of liquid biphasic- and ionic liquid technologies for the downstream processing of carotenoids such as astaxanthin and fucoxanthin from different microalgae strains. This thesis firstly introduces the application of liquid biphasic flotation system in the extraction and partitioning of astaxanthin from Haematococcus pluvialis microalgae. The optimized liquid biphasic flotation system is further employed with ultrasound- and electropermeabilization-assisted technologies for a simultaneous pretreatment and extraction of carotenoids from microalgae. These integrated technologies with liquid biphasic flotation system provide a one-step rapid processing, environmentally friendly, achieved higher yield and separation efficiency. In fact, the integrated technologies liquid biphasic flotation system was scale-up to investigate the feasibility for large scale and commercializing its usage for industrial proposes. This thesis also presented a greener and sustainable solvent using ionic liquids technology for the cell permeabilization and extraction of astaxanthin and fucoxanthin from microalgae. The green concept of the proposed ionic liquid in this research work utilized carbon dioxide as one of its reactants and they can be easily separated from the extracted bioproduct compared to conventional imidazole- and pyridinium-based ionic liquids. The characterization of the synthesized ionic liquid was comprehensively evaluated in this work. Besides, the cellular and surface morphology after treated with the ionic liquid were investigated. This work also illustrated the recyclability studies of the proposed ionic liquid for subsequent extraction. Moreover, the antioxidant properties of the extracted astaxanthin and fucoxanthin were subjected for antioxidant analysis. The research achievements in these works and future opportunities are highlighted in the last chapter of the thesis.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Show, Pau Loke
Khoiroh, Ianatul
Keywords: microalgae cell; carotenoids; biofuels; biomass; ionic liquid technologies; liquid biphasic flotation system
Subjects: T Technology > TP Chemical technology
Faculties/Schools: University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Chemical and Environmental Engineering
Item ID: 65593
Depositing User: Khoo, Kuan
Date Deposited: 04 Aug 2021 04:42
Last Modified: 04 Aug 2021 04:42

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