Superior removal of arsenic from water with zirconium metal-organic framework UiO-66.

Chenghong Wang,Xinlei Liu,J Paul Chen,Kang Li

doi:10.1038/srep16613

Chenghong Wang, Xinlei Liu + Show 2 more

Open Access

https://doi.org/10.1038/srep16613

Copy DOI

Abstract

In this study, water stable zirconium metal-organic framework (UiO-66) has been synthesized and for the first time applied as an adsorbent to remove aquatic arsenic contamination. The as-synthesized UiO-66 adsorbent functions excellently across a broad pH range of 1 to 10, and achieves a remarkable arsenate uptake capacity of 303 mg/g at the optimal pH, i.e., pH = 2. To the best of our knowledge, this is the highest arsenate As(V) adsorption capacity ever reported, much higher than that of currently available adsorbents (5–280 mg/g, generally less than 100 mg/g). The superior arsenic uptake performance of UiO-66 adsorbent could be attributed to the highly porous crystalline structure containing zirconium oxide clusters, which provides a large contact area and plenty of active sites in unit space. Two binding sites within the adsorbent framework are proposed for arsenic species, i.e., hydroxyl group and benzenedicarboxylate ligand. At equilibrium, seven equivalent arsenic species can be captured by one Zr6 cluster through the formation of Zr-O-As coordination bonds.

Highlights

Metal-organic frameworks (MOFs), a new class of hybrid porous materials built from organic linkers and inorganic metal nodes through coordination bonds[17], have attracted tremendous attention in recent years[18]
ZIF-8, MIL-53 and Fe-BTC MOF materials were put into aquatic arsenic removal tests[30,31,32], but no outstanding performance was observed in comparison with other commercial and synthetic adsorbents
To the best of our knowledge, this is the first work of applying zirconium MOFs (Zr-MOFs) in arsenic pollutant removal from water

Summary

Introduction

Metal-organic frameworks (MOFs), a new class of hybrid porous materials built from organic linkers and inorganic metal (or metal-containing cluster) nodes through coordination bonds[17], have attracted tremendous attention in recent years[18]. Benefitting from their versatile architectures and customizable chemical functionalities, MOFs have been widely applied in gas storage, sensing, catalysis, separation, etc[19,20,21,22,23]. The high degree of topological connectivity together with the strong coordination bonds between zirconium and oxygen renders UiO-66 to be greatly hydro-stable, even under acidic or some alkaline conditions[35] This provides a theoretical basis of applying UiO-66 in water treatment. This study unveils the excellent performance of UiO-66 adsorbent in arsenic removal from water, which would provide significant new insights to the application of MOFs in water treatment and lead to an advanced adsorbent material in arsenic decontamination industry

Methods

Results

Conclusion