A strategy to facilitate the sedimentation and bactericidal properties of polypyrrole for fluoride removal from water

Abstract

To facilitate the separation and bactericidal properties of polypyrrole (PPy) for fluoride removal from water, Ag@PPy composites with nanofiber morphology were successfully fabricated by direct redox reaction of pyrrole monomer and silver ion in acidic solution. The reduced silver is evenly distributed in Ag@PPy composites and accounts for 70 wt%. SBET and aperture size of Ag@PPy composites have no obvious variation compared with that of primitive PPy, but the isoelectric point is up to 6.68 from 4.30 (PPy). The settlement experiment indicated the good separation performance of the Ag@PPy composites from water. Subsequently, the Ag@PPy composites were applied to remove fluoride ions from water, and the fluoride adsorption process by Ag@PPy composites is pH-dependent, stability and recyclability. Furthermore, the Ag@PPy composites exhibit high affinity for fluoride ions and the adsorption process is kinetic fast within 60 min to reach equilibrium. The adsorption mechanism of fluoride ions onto Ag@PPy composites was investigated by X-ray photoelectron spectroscopy (XPS), flourier transformation infrared spectroscopy (FT-IR), and energy dispersive X-ray spectrometry (EDX). Meanwhile, the Kirby-Bauer disc diffusion method and the colony count method were used to evaluate the antibacterial property of the Ag@PPy composites. The results illustrated that the fluoride adsorption onto Ag@PPy composites is mainly an ion exchange mechanism, and the introduction of silver into the Ag@PPy composites enhanced the separation performance, adsorption stability and antibacterial property of PPy.