Design and Synthesis of Cross-Linked Micellar Particles to Assist Microalgae Lipid Recovery from Aqueous Extract

A series of cross‐linked micellar particles (CLMP) with internal hydrophobic binding sites was synthesized via a double‐cross‐link concept. A quaternary ammonium surfactant was first synthesized from natural tung oil. With two acrylate groups in the head group and conjugated alkenes in the hydrophobic tail, the surfactant was doubly cross‐linked in the micellar form on both the micellar surface and in the core. Surface cross‐linking at ambient temperature and core cross‐linking at 80 °C yielded 61 % final product (with 40 % space holder). The product and its morphology were characterized by infrared (IR) spectroscopy and scanning electron microscopy (SEM). The chemical nature and functional groups were confirmed by IR, and SEM indicated heterogeneous nanoparticles aggregated into clusters of particles. The binding capacity and selectivity of CLMP for microalgae lipids extracted from Nannochloropsis sp. were investigated and quantified using a turbidity test and mass spectrometry. The best CLMP product was able to extract total algae lipids at 0.8 g lipids/g particles capacity. At a lipid loading above the binding capacity, the CLMP selectively bound non‐charged polar lipids instead of the negatively charged polar lipids. These micellar particles have been demonstrated to be promising materials for extracting lipids from aqueous lipid extract. This paper presents a proof of concept study, and more in‐depth investigation is needed to test lipid extraction from various media and potentials for lipid class separation using these structured particles.