Sequestration of Metal Cations with Zerovalent Iron NanoparticlesA Study with High Resolution X-ray Photoelectron Spectroscopy (HR-XPS)

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707

作者：

Li, X.-q.，Zhang, W.-x.

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摘要：

Applications of nanoscale zerovalent iron (nZVI) for removal of metal cations in water are investigated with the result that nZVI has much larger capacity than conventional materials for the sequestration of Zn(II), Cd(II), Pb(II), Ni(II), Cu(II), and Ag(I). Characterizations with high-resolution X-ray photoelectron spectroscopy (HR-XPS) confirm that the iron nanoparticles have a coreshell structure, which leads to exceptional properties for concurrent sorption and reductive precipitation of metal ions. For metal ions such as Zn(II) and Cd(II) with standard potential E0 very close to or more negative than that of iron (0.41 V), the removal mechanism is sorption/ surface complex formation. For metals with E0 greatly more positive than iron, for instance Cu(II), Ag(I), and Hg(II), the removal mechanism is predominantly reduction. Meanwhile, metals with E0 slightly more positive than iron for example Ni(II) and Pb(II) can be immobilized at the nanoparticle surface by both sorption and reduction. The dual sorption and reduction mechanisms on top of the large surface of nanosized particles produce rapid reaction and high removal efficiency, and offer nZVI as an efficient material for treatment and immobilization of toxic heavy metals.

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关键词：

Experimental/ cadmium copper iron lead nanoparticles nickel positive ions precipitation (physical chemistry) reduction (chemical) silver sorption X-ray photoelectron spectra zinc/ metal cation sequestration zerovalent iron nanoparticles high resolution X-ray photoelectron spectroscopy metal cations Zn(II) ion Cd(II) ion Pb(Il) ion Ni(II) ion Cu(II) ion Ag(I) ion core-shell structure sorption reductive precipitation metal ions sorption-surface complex formation nanoparticle surface toxic heavy metal immobilization Hg(II) ion Cd - Element Pb - Element Ni - Element Cu - Element Ag - Element Zn - Element Hg - Element Fe - Element standard potential/ A7960C Photoelectron spectra of clean metals A8265M Sorption and accommodation coefficients (surface chemistry) A8230 Specific chemical reactions reaction mechanisms/ Cd/el Pb/el Ni/el Cu/el Ag/el Zn/el Hg/el Fe/el