The enhanced reduction of bromate by highly reactive and dispersive green nano-zerovalent iron (G-NZVI) synthesized with onion peel extract

In this study, novel green nano-zerovalent iron (G-NZVI) is synthesized for the first time using onion peel extract for the prevention of rapid surface oxidation and the enhancement of particle dispersibility with a high reductive capacity. The results from various surface analyses revealed that the spherical shape of G-NZVI was fully covered by the onion peel extract composed of polyphenolic compounds with C[double bond, length as m-dash]C–C[double bond, length as m-dash]C unsaturated carbon, C[double bond, length as m-dash]C, C–O, and O–H bonds, resulting in high mobility during column chromatography. Furthermore, the obtained G-NZVI showed the complete removal of 50 mg L(−1) of bromate (BrO(3)(−)) in 2 min under both aerobic (k = 4.42 min(−1)) and anaerobic conditions (k = 4.50 min(−1)), showing that G-NZVI had outstanding oxidation resistance compared to that of bare NZVI. Moreover, the observed performance of G-NZVI showed that it was much more reactive than other well-known reductants (e.g., Fe and Co metal organic frameworks), regardless of whether aerobic or anaerobic conditions were used. The effects of G-NZVI loading, the BrO(3)(−) concentration, and pH on the BrO(3)(−) removal kinetics using G-NZVI were also investigated in this study. The results provide the novel insight that organic onion peel waste can be reused to synthesize highly reactive anti-oxidative nanoparticles for the treatment of inorganic chemical species and heavy metals in water and wastewater.