Magnetic nanoparticle-enhanced supported liquid membrane contactors: Advanced tertiary amine integration for long-chain fatty acids recovery in Chlorella vulgaris biorefineries

Renewable energy sources, particularly biofuels like biodiesel, offer sustainable alternatives to fossil fuels. Microalgae are promising biofuel source because of their rapid growth and ability to produce lipids from CO₂, photoenergy, and nutrients. Magnetic nanoparticle-based flocculants, especially those modified with cationic surfactants, have gained attention because of their high efficiency and ease of recovery. In this study, the synthesized Fe₃O₄@MIL-100(Fe)@TEOS@CTAB (FMTC) demonstrated a high microalgae harvesting efficiency of 98% and an intracellular ATP concentration of 1.17 mM. Essential long-chain fatty acids (LCFAs) for biofuel production, namely oleic and linoleic acids, were extracted at concentrations of 9.32 mg/g DCW and 8.25 mg/g DCW, respectively. FMTC showed significant potential for reuse after re-functionalization using cetyltrimethylammonium bromide (CTAB) maintaining an average harvesting efficiency of 81.7% after functionalization. This reusability enhances the cost-effectiveness of FMTC for industrial applications. Furthermore, integration of supported liquid membrane contactor (SLMC) technology improved the recovery efficiencies of oleic and linoleic acids to 40.5% and 31.3%, respectively, supporting scalable LCFAs extraction from microalgae. The combination of FMTC with SLMC technology provides an efficient and scalable solution for biofuel production, reducing the need for additional chemical processing and enhancing the economic feasibility of large-scale production. The reusability of FMTC and the improved recovery efficiency of SLMC contribute to lower operational costs, facilitating the commercialization and sustainability of biofuel production. This integrated approach advances sustainable energy solution by promoting cost-effective and scalable biofuel production and reducing the dependence of fossil fuels.