Nanoencapsulation of arsenate with nanoscale zero-valent iron(nZVI):A 3D perspective

作     者：Airong Liu Wei Wang Jing Liu Rongbing Fu Wei-xian Zhang 

作者机构：State Key Laboratory for Pollution Control and Resource ReuseCollege of Environmental Science and EngineeringTongii UniversityShanghai 200092China School of Chemical Sdence and EngineeringTongji UniversztyShanghai 200092China Shanghai Institute of Pollution Control and Ecological SecurityShanghai 200092China 

出 版 物：《Science Bulletin》 (科学通报（英文版）)

年 卷 期：2018年第63卷第24期

页      面：1641-1648页

核心收录：

学科分类：07[理学] 

基　　金：the National Natural Science Foundation of China(11475127,51578396,41673096,and 41772243) National Postdoctoral Program for Innovative Talents(BX201700172) 

主　　题：Arsenate Nanoscale zero-valent iron Spherical aberration corrected scanning transmission electron microscopy X-ray energy-dispersive spectroscopy Electron energy-loss spectroscopy X-ray photoelectron spectroscopy 

摘      要：The principal forces driving the efficient enrichment and encapsulation of arsenic(As) into nanoscale zero-valent iron(nZVI) are the disordered arrangement of the atoms and the gradient chemical potentials within the core-shell interface. The chemical compositions and the fine structure of nZVI are characterized with a combination of spherical aberration corrected scanning transmission electron microscopy(Cs-STEM), X-ray energy-dispersive spectroscopy(XEDS), electron energy loss spectroscopy(EELS), and high-resolution X-ray photoelectron spectroscopy(HR-XPS). Atomically resolved EELS at the oxygen K-edge unfolds that the Fe species in nZVI are well stratified from Fe(Ⅲ) oxides in the outermost periphery to a mixed Fe(Ⅲ)/Fe(Ⅱ) interlayer, then Fe(Ⅱ) oxide and the pure Fe(0) phase. Reactions between As(Ⅴ)and nZVI suggest that a well-structured local redox gradient exists within the shell layer, which serves as a thermodynamically favorable conduit for electron transfer from the iron core to the surface-bound As(Ⅴ). HR-XPS with ion sputtering shows that arsenic species shift from As(Ⅴ), As(Ⅲ)/As(Ⅴ) to As(Ⅴ)/As(Ⅲ)/As(0) from the iron oxide shell–water interface to the Fe(0) core. Results reinforce previous work on the efficacy of nZVI for removing and remediating arsenic while the analytical TEM methods are also applicable to the study of environmental interfaces and surface chemistry.