Nano-zero-valent Fe/Ni particles loaded on collagen fibers immobilized by bayberry tannin as an effective reductant for uranyl in aqueous solutions

In this study, nano-zero-valent Fe/Ni particles (NZFNP) loaded on collagen fibers through the immobilization of bayberry tannin was prepared and used for uranium adsorption-reduction from aqueous solution. The effects of environmental conditions for uranium removal onto NZFNP were studied in detail. The as-prepared adsorbent was characterized by TEM, SEM, EDS, FT-IR to investigated the adsorption-reduction mechanism of uranium on NZFNP. The results indicated that the major removal reaction of uranium should be recognized as a process of adsorption and reduction, and the U(VI) was adsorbed onto NZFNP firstly under the effect of electrostatic interaction. Then the Fe-0 in the inner layer of the metal sphere lost electrons to generate Fe(II) as a new reductant, and U(VI) could be reduced by the Fe(II) generated on the surface of sample at the interface between adsorbent and aqueous. In particular, a higher uranium reduction ratio of 70.6% have been obtained due to the introduction of Ni-0, where a battery is formed between Fe-0 and Ni-0, thereby forming a continuous electron flow and an increase in Fe-0 activity. Thus, the NZFNP is promising for the rapid and effective removal of uranium from waste water.