Surfactant-assisted algal flocculation via aggregation-induced emission with an ultralow critical micelle concentration

Abstract

Surfactant-assisted algal flocculation has become a significant technique in the algal biodiesel industry. Generally, commercially available surfactants with longer chains are employed for algal flocculation owing to their lower critical micelle concentration (CMC). However, the efficiency of algal flocculation is unsatisfactory even at high concentrations of surfactants. In this work, an aggregation-induced emission surfactant, tetraphenylethene-dodecyltrimethylammonium bromide (TPE-DTAB), was used to flocculate Chlorella vulgaris C4 with high efficiency as a result of its ultralow CMC (24 μM) derived from the hydrophobic and rigid tetraphenylethene moiety. More interestingly, TPE-DTAB could generate fluorescence in its aggregation state in comparison with conventionally nonluminous surfactants. Therefore, the entire flocculation process of TPE-DTAB micelles with algae has been visualized. Our results would be helpful for scientists to design suitable surfactants with ultralow CMC for high-efficiency algal flocculation.