Xie Li, Shang Chii
Department of Civil Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
Chemosphere. 2006 Aug;64(6):919-30. doi: 10.1016/j.chemosphere.2006.01.042. Epub 2006 Feb 28.
Bromate reduction by Fe(0) with incorporation of copper or palladium was investigated in batch tests. The incorporation of copper led to an increase in the rate of bromate reduction, while incorporation of palladium did not show any effect on bromate reduction by Fe(0), regardless of the bimetal application techniques (either simultaneous addition of Cu(II) or Pd(IV) into the Fe-BrO3- reaction system or using copper or palladium amended iron for bromate removal). Surface analyses by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) techniques indicated that aqueous Cu(II) was reduced and incorporated into the iron surface to form Cu2O and Cu(0). Among these two species, pure Cu(0) is not an active electron donor to the bromate reduction reaction, as shown by there being no reduction from using Cu(0) powders alone and no enhancement by Fe(0) when physically mixed with Cu(0). Although it has been proposed in the literature that the enhancement of adsorption also contributes to the enhancement of chemical reduction, this is not the case here because adsorption decreased when Cu increased. The enhanced bromate reduction rate in the presence of copper observed here is most likely the result of the newly formed active Cu(I). The presence of PdO was evidenced by XPS but yielded no enhancement in bromate reduction. Finally, the Cu2O present on the iron surface because of copper impurities in commercially available iron was found to be involved in the bromate reduction and to accelerate the reduction rate.
通过分批试验研究了铁（0）在掺入铜或钯的情况下对溴酸盐的还原作用。掺入铜导致溴酸盐还原速率增加，而掺入钯对铁（0）还原溴酸盐没有任何影响，无论双金属应用技术如何（即向Fe-BrO3-反应体系中同时添加Cu（II）或Pd（IV），或者使用经铜或钯改性的铁来去除溴酸盐）。通过X射线光电子能谱（XPS）和X射线粉末衍射（XRD）技术进行的表面分析表明，水溶液中的Cu（II）被还原并掺入铁表面，形成Cu2O和Cu（0）。在这两种物质中，纯Cu（0）不是溴酸盐还原反应的活性电子供体，这表现为单独使用Cu（0）粉末时没有还原现象，并且当与Cu（0）物理混合时Fe（0）也没有增强作用。尽管文献中提出吸附增强也有助于化学还原增强，但这里并非如此，因为当铜增加时吸附会降低。此处观察到的在铜存在下溴酸盐还原速率的提高最有可能是新形成的活性Cu（I）的结果。XPS证明了PdO的存在，但它并未提高溴酸盐的还原率。最后，发现由于市售铁中的铜杂质而存在于铁表面的Cu2O参与了溴酸盐的还原并加快了还原速率。
