Magnetic phosphorylated chitosan composite as a novel adsorbent for highly effective and selective capture of lead from aqueous solution.

Separating and recovering lead from heavy metal contaminated wastewater is crucial for the environment remediation and reutilization of lead resources. Herein, a novel adsorbent, the phosphorylated chitosan-coated magnetic silica nanoparticles (Fe3O4@SiO2@CS-P), was successfully fabricated and applied to highly selective adsorption of lead. Competitive experiments were conducted in a multi-ion solution (7 metal ions coexist) at pH 6.0, Fe3O4@SiO2@CS-P exhibited an excellent selectively for capturing lead with the distribution coefficient (0.75 L g-1) more ten times than other metal, while Fe3O4@SiO2@CS demonstrated a highly selective adsorption of silver. These implied that phosphorylation of adsorbent not only improves the sorption performance of lead, but also changes the selective adsorption of metal types. Acidity experiments can draw conclusions that Fe3O4@SiO2@CS-P exhibited better acid resistance (with barely any iron leaching) than silica-uncoated adsorbent (Fe3O4@CS-P) at pH 1.0. Furthermore, the FTIR and XPS spectra after adsorption suggested that the high adsorption performance and selective capture lead were predominantly controlled by the coordination of the phosphate groups on the surface of the adsorbent. This work shows a broad prospect of developing a series of novel, acid-resistant, good reusable and rapidly separable magnetic materials that can be used to efficiently and selectively capture lead from aqueous solutions.