Preparation of montmorillonite/chitosan/γ-polyglutamic acid nanoparticles and evaluation of their adsorption and antibacterial performance

In this study, montmorillonite (MMT)/chitosan (CS)/γ-polyglutamic acid (γ-PGA) nanoparticles were synthesized using MMT, CS, and γ-PGA as the matrix materials, with amino silane as the crosslinking agent. Through single-factor and response surface methodology experiments, the optimal nanoparticle formulation was determined by measuring the particle size and zeta potential of the composite nanoparticles. The synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy, and their heavy-metal (Co²⁺) adsorption capacity and antibacterial (Escherichia coli) performance were evaluated. The results indicated that the optimal MMT/CS/γ-PGA nanoparticle formulation was obtained when the MMT concentration was 2.18 mg/mL, CS concentration was 2 mg/mL, and γ-PGA/CS mass ratio was 1:4 in a 100 mL aqueous solution. Under these conditions, the average particle size was 899.76 nm, and the zeta potential was 60.57 mV. During Co²⁺ adsorption tests, adsorption equilibrium was achieved at 135 min, with the nanoparticles demonstrating an adsorption capacity of 17.4 mmol/g at an initial cobalt concentration of 80 mmol/L. However, antibacterial activity tests revealed very weak antibacterial effects of the nanoparticles against E. coli. Overall, this study provides theoretical support for the preparation and application of eco-friendly nanoparticles with potential use in heavy-metal adsorption.