Effect of Spatial Distribution of nZVI on the Corrosion of nZVI Composites and Its Subsequent Cr(VI) Removal from Water.

Yixuan Li,Yaqin Song,Xinfang Zhang,Sijia Liu,Qiong Du,Shuangqiu Huang

doi:10.3390/nano12030494

Abstract

There have been many studies on contaminant removal by fresh and aged nanoscale zero-valent iron (nZVI), but the effect of spatial distribution of nZVI on the corrosion behavior of the composite materials and its subsequent Cr(VI) removal remains unclear. In this study, four types of D201-nZVI composites with different nZVI distributions (named D1, D2, D3, and D4) were fabricated and pre-corroded in varying coexisting solutions. Their effectiveness in the removal of Cr(VI) were systematically investigated. The results showed acidic or alkaline conditions, and all coexisting ions studied except for H2PO4− and SiO32− enhanced the corrosion of nZVI. Additionally, the Cr(VI) removal efficiency was observed to decrease with increasing nZVI distribution uniformity. The corrosion products derived from nZVI, including magnetite, hematite, lepidocrcite, and goethite, were identified by XRD. The XPS results suggested that the Cr(VI) and Cr(III) species coexisted and the Cr(III) species gradually increased on the surface of the pre-corroded D201-nZVI with increasing iron distribution uniformity, proving Cr(VI) removal via a comprehensive process including adsorption/coprecipitation and reduction. The results will help to guide the selection for nZVI nanocomposites aged under different conditions for environmental decontamination.

Highlights

As an environmentally functional material, zero-valent iron (ZVI) has been widely used for in situ pollution remediation because of its high reactivity, low price, and environmental friendliness [1]
With the increase in reductant (KBH4 ) concentration from 0.9% to 7.2%, the iron distribution of D201nZVI gradually shifted from the outside of the resin to the core area, indicating that the uniformity of the iron distribution in the resin notably improved from D1 to D4
It could be seen the details of four types of D201-nanoscale zero-valent iron (nZVI) at 100 nm that demonstrated nanoscale iron were well dispersed on the surface and interior of the D201 resin

Summary

Introduction

As an environmentally functional material, zero-valent iron (ZVI) has been widely used for in situ pollution remediation because of its high reactivity, low price, and environmental friendliness [1]. The weaknesses, including poor stability, difficult separation, and rapid passivation, remarkably limit the effectiveness of nZVI and its practical application [2]. To counteract these drawbacks, an effective approach is to immobilize nZVI into porous materials such as activated carbon [3], bentonite [4], kaolinite [5], chitosan [6], and exchange resin [7], which can be used as a carrier to support nZVI with good mechanical strength and adjustable pore structure.

Methods

Results

Conclusion