Fe0-Fe3O4 nanocomposites embedded polyvinyl alcohol/sodium alginate beads for chromium (VI) removal

In this study, Fe 0 -Fe 3 O 4 nanocomposites embedded polyvinyl alcohol (PVA)/sodium alginate (SA) beads were synthesized, which exhibited an excellent physical properties and catalytic reactivity, and a robust performance of post-separation (complete separation using a simple grille) and reusability (efficiency of 69.8% after four runs) in Cr(VI) removal. 5.0   wt% PVA with 1.5   wt% SA was the optimal proportion for beads molding, and the followed acidification and reduction treatments were critical to ensure high mechanical strength and high Cr(VI) removal ability of beads. Effects of Fe 0 and Fe 3 O 4 mass fraction, initial pH and Cr(VI) concentration on final removal efficiency were also evaluated. Merely 0.075   wt% Fe 0 together with 0.30   wt% Fe 3 O 4 was sufficient to deal with 20   mg   L −1 Cr(VI) solution. The efficiency decreased from 100 to 79.5% as initial Cr(VI) increased from 5 to 40   mg   L −1 , while from 99.3 to 76.3% with increasing pH from 3.0 to 11.0. This work provides a practical and high-efficient method for heavy metal removal from water body, and simultaneously solves the problems in stabilization, separation and regeneration of Fe 0 nanoparticles.