Design of Scorodite@Fe3O4 Core–Shell Materials and the Fe3O4 Shell Prevents Leaching of Arsenic from Scorodite in Neutral and Alkaline Environments

Yang Wang,Xincun Tang,Shan Cao,Zhihao Rong

doi:10.3390/coatings9080523

Yang Wang, Xincun Tang + Show 2 more

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https://doi.org/10.3390/coatings9080523

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Journal: Coatings	Publication Date: Aug 16, 2019
Citations: 5	License type: CC BY 4.0

Affiliation: Central South University, Qilu University of Technology

Abstract

In recent years, arsenic pollution has seriously harmed human health. Arsenic-containing waste should be treated to render it harmless and immobilized to form a stable, solid material. Scorodite (iron arsenate) is recognized as the best solid arsenic material in the world. It has the advantages of high arsenic content, good stability, and a low iron/arsenic molar ratio. However, scorodite can decompose and release arsenic in a neutral and alkaline environment. Ferroferric oxide (Fe3O4) is a common iron oxide that is insoluble in acid and alkali solutions. Coating a Fe3O4 shell that is acid- and alkali-resistant on the surface of scorodite crystals will improve the stability of the material. In this study, a scorodite@Fe3O4 core–shell structure material was synthesized. The synthesized core–shell material was detected by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman, and energy-dispersive X-ray spectroscopy (EDS) techniques, and the composition and structure were confirmed. The synthesis condition and forming process were analyzed. Long-term leaching tests were conducted to evaluate the stability of the synthesized scorodite@Fe3O4. The results indicate that the scorodite@Fe3O4 had excellent stability after 20 days of exposure to neutral and weakly alkaline solutions. The inert Fe3O4 shell could prevent the scorodite core from corrosion by the external solution. The scorodite@Fe3O4 core–shell structure material was suitable for the immobilization of arsenic and has potential application prospects for the treatment of arsenic-containing waste.

Highlights

Arsenic is a toxic element because it is bioaccumulative and carcinogenic [1,2,3]
The synthesized core–shell material was detected by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman, and energy-dispersive X-ray spectroscopy (EDS)
The main peaks were located at approximately 19.8◦, 28.0◦, 15.8◦, and 29.1◦, which were respectively indexed as the (200), (212), (111), and (131) lattice planes of scorodite (FeAsO4 ·2H2 O, JCPDS No 37-0468) [37]

Summary

Introduction

Arsenic is a toxic element because it is bioaccumulative and carcinogenic [1,2,3]. It has been reported that there is a worldwide arsenic problem in the groundwater of more than 20 countries and regions [4].In recent years, arsenic poisoning has occurred frequently and arsenic pollution has seriously harmed human health [5,6]. It has been reported that there is a worldwide arsenic problem in the groundwater of more than 20 countries and regions [4]. The problem of arsenic pollution has attracted wide attention [7,8]. There are very few arsenic compounds in nature; most of the arsenic is symbiotic in the form of sulfides in nonferrous metal ores [9]. Arsenic is brought into industrial systems as part of the mining and smelting of nonferrous metal ore [10,11]. Most of the arsenic pollution comes from the nonferrous metal smelting industry [12]. Nonferrous metal smelting is the main source of arsenic-containing waste [13]. Improper disposal of arsenic-containing waste is one of the important causes of arsenic contamination [14]

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