Effective removal of nanoplastics from water by cellulose/MgAl layered double hydroxides composite beads

Abstract

Micro/nanoplastic pollution is an emerging concern all over the world as it has a certain impact on the eco-environment and human health. In this study, cellulose/MgAl layered double hydroxides (LDHs) composite beads were prepared for the removal of polystyrene nanoparticles by utilizing the porous properties of cellulose and the unique positive charge of LDHs. The effects of pH, contact time, initial concentration, temperature, humic acid, and ionic strength on the attachment of nanoplastics were studied. The microstructure characteristics of the beads were also analyzed before and after the attachment of nanoplastics. The results indicate that nanoplastic attachment probably involves pore diffusion, hydrogen bonding, and electrostatic interactions. The attachment behavior can be successfully explained using the pseudo-second-order kinetic model (R² = 0.964), Webber-Morris (intra-particle diffusion) model, and Langmuir isotherm model (R² = 0.978). The maximum attachment capacity can reach 6.08 mg/g. Therefore, the cellulose/LDHs composite beads can be a promising adsorbent for removing micro/nanoplastics.

Keywords: Attachment; Cellulose; Layered double hydroxides; Nanoplastics.