Surface nano-traps of Fe0/COFs for arsenic(III) depth removal from wastewater in non-ferrous smelting industry

The chemical valence state of arsenic changed with the redox state which influenced by the aquatic environmental factors. One challenge for arsenic control is the depth removal of trivalent arsenic (As(III)) from wastewater from non-ferrous industries. Immobilization of As(III) could be realized through an enhanced adsorption method. In this study, zero-valent iron (Fe-0) nanoparticles assembled on porous covalent organic frameworks (COFs) were selected as "nanotraps" for arsenic ions capture and surface stabilization. Fe-0/TAPB-PDA COFs composites were synthesized through an in-situ growth method. The porous surface of COFs offered efficient spaces for Fe-0 loading as well as the reaction sites. The results showed that Fe-0/COFs exhibited a better performance in As(III) adsorption than pure nZVI (nanoscale zero-valent iron), and the maximum adsorption capacity reached to 135.78 mg/g. In addition, the effects of co-existed anions and metal ions were also investigated. Such a novel composite exhibited a huge potential for heavy metals purification in future study.