β-Cyclodextrin functionalized magnetic nanoparticles for the removal of pharmaceutical residues in drinking water

Abstract

Trace amounts of pharmaceuticals and personal care products (PPCPs) are found in our water systems, and they are known to have adverse effects on wildlife and human at the ng/L to μg/L range, below the detection limit of most water analytical instruments. Methacrylate acid (MAA)-ethyl acrylate (EA) colloidal scaffolds were prepared via emulsion polymerization and used as templates for the in-situ co-precipitation of Fe2+ to produce stable functional magnetic nanoparticles (MNPs) (<500 nm) decorated with β-cyclodextrin (β-CD) (FMNP). Emulsion polymerization with the controlled addition of monomer mixtures allowed for good size control, and silica coating was introduced to prevent the oxidation of FMNP. The superparamagnetic FMNP with high saturation magnetization (33 emu/g) could be readily separated from water using a high gradient magnetic separator (HGMS). Procaine hydrochloride (PrHy) was used as a model pharmaceutical residue to evaluate the performance of the FMNP, and 53.65 mg PrHy/g FMNP was absorbed using 600 ppm FMNP. A fast (30 min) adsorption kinetic follows the Pseudo-first-order kinetic model that described the physical adsorption through a 1 to 1 host–guest inclusion mechanism. And the adsorption behavior followed the Freundlich isotherm with a linear adsorption performance. The proposed system is scalable and adaptable to existing water treatment processes, and it can be used for the detection of low concentration pharmaceuticals via a pre-concentrating strategy.