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采用液相还原法制备膨润土负载纳米铁(B-NZVI),并用十六烷基三甲基溴化铵(CTMAB)对其进行表面改性,研究了不同n(FeSO4)/n(NaBH4)(记为N)制备的(B-NZVI)/CTMAB的除铬效果。结果表明,N=1时制备的(B-NZVI)/CTMAB除Cr(Ⅵ)效率最高,较未改性的膨润土负载纳米铁(B-NZVI)的除Cr(Ⅵ)效率(57.7%)提高了23.7%,反应速率提高1.31倍。X射线衍射发现,N=1时不仅有零价铁,还有Fe(Ⅱ),对加快反应速率和提升去除效果有一定作用。从反应后产物的光电子能谱(XPS)图看出Cr(Ⅵ)被吸附后大部分还原为Cr(Ⅲ),而铁被氧化为Fe(Ⅲ)。最后,结合反应前后材料的表面电性以及扫描电镜图,对(B-NZVI)/CTMAB改性机制、改性后纳米零价铁线的形成及去除Cr(Ⅵ)的机理和产物等进行了探究。
The bentonite supported nano-iron (B-NZVI) was prepared by liquid-phase reduction method and its surface was modified by cetyltrimethylammonium bromide (CTMAB). The effects of different n (FeSO4) / n Recorded as N) prepared (B-NZVI) / CTMAB chromium removal effect. The results show that (B-NZVI) / CTMAB has the highest Cr (Ⅵ) removal efficiency except B-NZVI (57.7%) than that of unmodified bentonite-supported nano-iron 23.7%, the reaction rate increased by 1.31 times. X-ray diffraction found that when N = 1, not only zero-valent iron, but also Fe (Ⅱ), to speed up the reaction rate and enhance the removal effect to a certain extent. The results of photoelectron spectroscopy (XPS) showed that most of Cr (VI) was reduced to Cr (III) and Fe was oxidized to Fe (III). Finally, the modification mechanism of (B-NZVI) / CTMAB, the formation of modified zero-valent nanowires and the mechanism of Cr (Ⅵ) removal and the products were studied by the surface electrical properties and scanning electron micrographs before and after the reaction Explore.