Polyethylene glycol-stabilized bimetallic nickel–zero valent iron nanoparticles for efficient removal of Cr(vi)

Abstract

In order to solve the agglomeration of nanoscale zero-valent iron (nZVI) and improve its performance in pollutant treatment, polyethylene glycol-stabilized nickel modified nZVI (Ni/Fe–PEG) was synthesized by a liquid-phase reduction method and used to treat Cr(VI) solution for the first time. The main influencing factors were optimized as follows: a Ni/Fe–PEG dosage of 0.6 g L⁻¹, an initial pH value of 5.0, and an initial Cr(VI) concentration of 50 mg L⁻¹. More than 99% of Cr(VI) is removed in 60 min. The excellent performance of Ni/Fe–PEG is attributed to its strong adsorption, reduction and co-precipitation. More specifically, Cr(VI) is first adsorbed on the surface of Ni/Fe–PEG, then reduced to Cr(III) by nZVI, and finally, Cr(III) and Fe(III) are co-precipitated. In Ni/Fe–PEG, PEG can disperse nZVI, while Ni can weaken the oxidation of nZVI and facilitate the reduction of Cr(VI).