Carbon capture through alkaline solvents coupled with conversion into bioplastics via microalgae: Towards a sustainable bioconversion pathway

The increasing concentration of atmospheric carbon dioxide (CO2) is a major contributor to global climate change, influencing the natural habitat of living organisms, economies, and overall public health, necessitating the development of efficient carbon capture and utilization strategies. This study explores an integrated biorefinery approach that combines CO2 capture using alkaline solvents with the biological conversion of captured CO2 into bioplastics via microalgae cultivation. The detailed mechanism of using alkaline hydroxides and carbonates to efficiently capture CO2 from flue gas emissions is explored, highlighting how this process generates a concentrated carbon source that promotes microalgal growth. The downstream processing of microalgae is also discussed to explore the use of physical, chemical, and biological harvesting techniques to maximize biomass recovery. Extraction and processing of key biopolymers like polyhydroxyalkanoates (PHAs) and polylactic acid (PLA) from different microalgal species is explained, which are further transformed into biodegradable plastics. Moreover, the potential of microalgae-based biorefineries to integrate wastewater treatment and captured CO2 for biomass production, yielding biofuels, energy, and high-value products, is demonstrated as a sustainable circular bioeconomy approach. This integrated approach not only enhances the efficiency of bioplastic production but also promotes the utilization of renewable resources, contributing to the development of environmentally friendly materials.