Chun Chan Lan, Penn R Lee, Arnold William A
Department of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, Minnesota 55455-0116, USA.
Environ Sci Technol. 2006 May 15;40(10):3299-304. doi: 10.1021/es0600983.
Reactions mediated by iron mineral surfaces play an important role in the fate of organic contaminants in both natural and engineered systems. As such reactions proceed, the size, morphology, and even the phase of iron oxide minerals can change, leading to altered reactivity. The reductive degradation of 4-chloronitrobenzene and trichloronitromethane by Fe(II) associated with goethite (alpha-FeOOH) was examined by performing sequential-spike batch experiments. The particle size and size distribution of the pre- and postreaction particles were quantified using transmission electron microscopy (TEM). Results demonstrate that the degradation reactions result in goethite growth in the c-direction. Furthermore, pseudo-first-order reaction rate constants for the degradation of 4-chloronitrobenzene and trichloronitromethane and for the loss of aqueous Fe(II) decrease dramatically with each subsequent injection of organic compound and Fe(II). This result indicates that the newly formed material, which TEM and X-ray diffraction results confirm is goethite, is progressively less reactive than the original goethite. These results represent an important step toward elucidating the link between mineral surface changes and the evolving kinetics of contaminant degradation at the mineral-water interface.
铁矿物表面介导的反应在自然和工程系统中有机污染物的归宿方面起着重要作用。随着此类反应的进行，氧化铁矿物的尺寸、形态甚至相都会发生变化，从而导致反应活性改变。通过进行连续加样批次实验，研究了与针铁矿（α-FeOOH）相关的Fe（II）对4-氯硝基苯和三氯硝基甲烷的还原降解作用。使用透射电子显微镜（TEM）对反应前后颗粒的粒径和粒径分布进行了量化。结果表明，降解反应导致针铁矿沿c轴方向生长。此外，随着有机化合物和Fe（II）的每次后续注入，4-氯硝基苯和三氯硝基甲烷降解以及水溶液中Fe（II）损失的准一级反应速率常数显著降低。这一结果表明，TEM和X射线衍射结果证实新形成的物质是针铁矿，其反应活性逐渐低于原始针铁矿。这些结果是朝着阐明矿物表面变化与矿物-水界面处污染物降解不断变化的动力学之间的联系迈出的重要一步。
