High-Level Extraction of Recyclable Nanocatalysts by Using Polyphosphazene Microparticles.

Improper disposal of metal nanoparticles has caused serious environmental and pathological problems because of their active nanotoxicity. Therefore, there is an urgent need to develop a strategy for efficiently removing redundant metal nanoparticles from water, while also permitting restoration of their catalytic activities to those of pristine particles for reapplication. Herein, we present intrinsically nitrogen-rich cross-linked polyphosphazene microparticles to capture silver nanoparticles (AgNPs) from aqueous media by a simple one-step method. The described microparticles exhibit an outstanding adsorption capacity for AgNPs of approximately 59.35 mg/g, exceeding those of other adsorbents. The adsorption kinetics of AgNPs on these microparticles obeyed a pseudo-second-order kinetic model. More importantly, the recovered AgNPs maintained good catalytic activity in the reduction of methylene blue by sodium borohydride. Based on their simple preparation, high adsorption efficiency, and nondestructive effect on the catalytic activity of the recovered AgNPs, the described polyphosphazene microparticles display promising potential for the removal and recovery of AgNPs from water.