Removal of polystyrene nanoparticles using MgAl layered double hydroxide membranes synthesized on aluminum plates

The accumulation of nanoplastics in aquatic environments, including tap and bottled water, necessitates the development of simple methods for nanoplastic removal. The objective of this study was to assess the efficacy of MgAl-type layered double hydroxide (LDH) membranes formed on aluminum plates in magnesium chloride (MgCl₂) solutions for ten min to remove nanoplastics from water. MgCl₂ concentrations of 25, 50, and 100 mM yielded three distinct MgAl-LDH films. The membranes were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Adsorption experiments were performed for 100 nm (PS100) and 1 μm (PS1) polystyrene nanoparticles with carboxyl groups. The results of kinetic studies indicated that the adsorption of PS100 followed a pseudo-second-order model, whereas that of PS1 followed a pseudo-first-order model. The equilibrium experiments were fitted to the Langmuir model, revealing that the LDH membrane synthesized in the 100 mM MgCl₂ solution exhibited the highest adsorption capacity for both PS100 and PS1. The sheet-like MgAl-LDH films were easily manipulated and demonstrated effective removal of nanoplastics from water, suggesting their potential applications in various fields. • LDH films were formed in MgCl₂ solutions on aluminum plates in 10 min. • Adsorption experiments were performed for 0.1 and 1 μm polystyrene nanoparticles. • The adsorption models were suggested by the results of kinetic studies. • The equilibrium experiments were fitted to the Langmuir mode. • The LDH synthesized in 100 mM MgCl₂ solution exhibited the highest adsorption.