Excellent capture of Pb(II) and Cu(II) by hierarchical nanoadsorbent Fe3O4@SiO2@PAA-SO3H: A combined experimental and theoretical study

A novel magnetic nanoadsorbent (Fe3O4@SiO2@PAA-SO3H) was synthesized by grafting acrylic acid and sulfonic group to Fe3O4@SiO2 using a facile cross-link technology. The adsorbent presented water-stability and biocompatibility in wastewater, which exhibited high-selectivity capture for Pb(II) and Cu(II) of 182.5 mg/g and 250.7 mg/g, respectively, at pH 6.0. Furthermore, the adsorption-desorption processes show that nanoadsorbent still retains high uptake capacity after 6 cycles, revealing structural stability and advanced recycling. Effects from other ions existed weak interference in removal of Pb(II) and Cu(II). Meanwhile, the mechanism was further analyzed from both electrostatic potential (ESP) and average local ionization energy (ALIE) based on the density functional theory (DFT). The results indicate that interaction among nanoadsorbent and heavy metal ions is bridged by oxygen active sites. As the Fe3O4@SiO2@PAA-SO3H adsorbent is a hierarchical, highly waterdispersible and biocompatible adsorbent, it is a potential new treatment option for wastewater.

Automated summary

In this study, a novel magnetic nanoadsorbent was successfully synthesized, which exhibited water stability and biocompatibility in wastewater, and showed high selective capture for Pb(II) and Cu(II). The nanoadsorbent retained high uptake capacity after multiple cycles and had weak interference from other ions. The mechanism of interaction between the nanoadsorbent and heavy metal ions was analyzed based on electrostatic potential and average local ionization energy. The results showed that the interaction was bridged by oxygen active sites. This hierarchical and highly water-dispersible nanoadsorbent has the potential to be used for wastewater treatment.