Mercury pollution has posed increasingly severe threat to environment all over the world. Dealing with the problem of mercury contamination in water bodies is extremely urgent. The iron-based nanoparticles like FeS_x、Fe₃O₄、Fe are used to remove mercury from aqueous solutions due to their high adsorption capacity and large surface area. In addition, using particle stabilization techniques and functional group modification could increase the dispersion of iron-based nanoparticles, offer more adsorption sites for the adsorption of mercury, which could enhance the effect of mercury removal. This paper emphasizes on the stabilization of FeS_x nanoparticles, thiol-functionalization and amino-functionalization of Fe₃O₄, etc. The applications of functionalized iron-based nano-materials are summarized. The influential factors of mercury removal by iron-based materials are further discussed, and then the adsorption mechanisms of mercury by functionalized iron-based nanoparticles are also explored. Finally, the outlook of mercury removal in water environment by modified iron-based nano-materials are presented.

Contents
1 Introduction
2 Functional iron sulfide
2.1 Bio-stabilizer stabilized iron sulfide
2.2 Supported iron sulfide
2.3 The mechanisms of mercury removal by iron sulfide
3 Functional magnetic iron-based materials
3.1 Thiol-functionalization
3.2 Amino-functionalization
3.3 Other functionalizations
3.4 The mechanisms of mercury removal by magnetic iron-based materials
4 Other iron-based materials
5 Conclusion