Silicate Derived from Phaeodactylum tricornutum for Removal of Polystyrene: Interfacial Effects of Living Organism and Its Derivatives with Nanoplastics

The deposition of nanoplastics in the environment poses a direct threat to human health through the food chain. There is an urgent need to investigate how they can be effectively removed from water. In this work, the toxic effects of nanopolystyrene (PS) at different concentrations on Phaeodactylum tricornutum (PT) were investigated. The results show that PS affects the cell activity of PT through cell wall adhesion and shading effect and hinders the transmission of light energy, thus inhibiting the growth of PT. Considering that living PT is not suitable for the removal of heterogeneous aggregation of PS, magnesium silicate (MS) was obtained by calcination of PT biomass based on retaining salt. The maximum adsorption capacity of PS by MS was 40.85 mg g–1, which was 10 times higher than that of conventional adsorbents. The presence of competitive anions significantly affects the removal of PS. The application in real water bodies and the reusability of the adsorbents were also verified. By characterizing the materials before and after adsorption, it is found that the adsorption mechanism mainly includes electrostatic attraction, hydrogen bonding, π–π interaction, and complexation between Si–O bond and PS. This study explains the toxic effect of nano-PS on PT and innovatively develops a biomass derivative from diatoms, which provides a novel and feasible strategy for environmental remediation.