Department of Environmental Engineering, National Chung-Hsing University, Taichung 402, Taiwan.
Sci Total Environ. 2010 Apr 15;408(10):2260-7. doi: 10.1016/j.scitotenv.2010.01.039. Epub 2010 Feb 16.
Nano-scale zero-valent iron (NZVI) has been shown to be suitable for remediating contaminated aquifers. However, they usually aggregate rapidly and result in a very limited migration distance that inhibits their usefulness. This study employed poly acrylic acid (PAA) and carboxymethyl cellulose (CMC) to synthesize two types of stabilized styles of NZVI with finer sizes (namely PNZVI and CNZVI). The mobility of stabilized NZVI was also demonstrated on the basis of transport in porous media. The results show that the PNZVI has a uniform particle size of 12 nm. However, tens of CNZVI particles with diameters of 1-3 nm were packed into secondary particles. Both the PNZVI and the CNZVI exhibited amorphous structures, and the stabilizer was bound to particle surfaces in the form of bidentate bridging via the carboxylic group, which could provide both electrostatic and steric repulsion to prevent particle aggregation. This study also proposes presumed stabilized configurations of PNZVI and CNZVI to reasonably illustrate their different dispersed suspension types. On the basis of the breakthrough curves and mass recovery, this study observed that the mobility of PNZVI in classic Ca(2+) concentration of groundwater was superior to CNZVI. Nonetheless, the mobility of CNZVI would be decreased less significantly than PNZVI when encountering high Ca(2+) concentrations (40 mM). Presumably, increasing the pore flow velocity would enhance the mobility of stabilized NZVI. Overall, the results of this study indicate that PNZVI has the potential to become an effective reactive material for in situ groundwater remediation.
纳米零价铁 (NZVI) 已被证明适用于修复受污染的含水层。然而，它们通常会迅速聚集，导致迁移距离非常有限，从而限制了它们的用途。本研究采用聚丙烯酸 (PAA) 和羧甲基纤维素 (CMC) 合成了两种具有更小粒径的稳定化 NZVI 类型 (即 PNZVI 和 CNZVI)。还基于在多孔介质中的传输来证明稳定化 NZVI 的迁移能力。结果表明，PNZVI 的粒径均匀，为 12nm。然而，数十个直径为 1-3nm 的 CNZVI 颗粒被包装成次级颗粒。PNZVI 和 CNZVI 均表现出无定形结构，稳定剂通过羧酸基团以双齿桥接的形式结合到颗粒表面，这可以提供静电和空间排斥作用以防止颗粒聚集。本研究还提出了 PNZVI 和 CNZVI 的假定稳定化构型，以合理说明它们不同的分散悬浮类型。根据穿透曲线和质量回收，本研究观察到 PNZVI 在经典地下水 Ca(2+) 浓度下的迁移能力优于 CNZVI。然而，当遇到高 Ca(2+) 浓度 (40mM) 时，CNZVI 的迁移能力下降幅度小于 PNZVI。据推测，增加孔隙流速会增强稳定化 NZVI 的迁移能力。总的来说，本研究的结果表明，PNZVI 有可能成为原位地下水修复的有效反应材料。
