Busch Jan, Meißner Tobias, Potthoff Annegret, Oswald Sascha E
University of Potsdam, Institute of Earth and Environmental Science, Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany.
Fraunhofer IKTS, Winterbergstraße 28, 01277 Dresden, Germany.
J Contam Hydrol. 2014 Aug;164:25-34. doi: 10.1016/j.jconhyd.2014.05.006. Epub 2014 May 27.
Injection of nanoscale zero-valent iron (nZVI) has recently gained great interest as emerging technology for in-situ remediation of chlorinated organic compounds from groundwater systems. Zero-valent iron (ZVI) is able to reduce organic compounds and to render it to less harmful substances. The use of nanoscale particles instead of granular or microscale particles can increase dechlorination rates by orders of magnitude due to its high surface area. However, classical nZVI appears to be hampered in its environmental application by its limited mobility. One approach is colloid supported transport of nZVI, where the nZVI gets transported by a mobile colloid. In this study transport properties of activated carbon colloid supported nZVI (c-nZVI; d50=2.4μm) are investigated in column tests using columns of 40cm length, which were filled with porous media. A suspension was pumped through the column under different physicochemical conditions (addition of a polyanionic stabilizer and changes in pH and ionic strength). Highest observed breakthrough was 62% of the injected concentration in glass beads with addition of stabilizer. Addition of mono- and bivalent salt, e.g. more than 0.5mM/L CaCl2, can decrease mobility and changes in pH to values below six can inhibit mobility at all. Measurements of colloid sizes and zeta potentials show changes in the mean particle size by a factor of ten and an increase of zeta potential from -62mV to -80mV during the transport experiment. However, results suggest potential applicability of c-nZVI under field conditions.
纳米零价铁（nZVI）注入作为一种从地下水系统中原位修复氯代有机化合物的新兴技术，最近引起了人们极大的兴趣。零价铁（ZVI）能够还原有机化合物并将其转化为危害较小的物质。由于纳米级颗粒具有高比表面积，使用纳米级颗粒而非颗粒状或微米级颗粒可使脱氯速率提高几个数量级。然而，传统的nZVI在环境应用中似乎因其迁移性有限而受到阻碍。一种方法是nZVI的胶体支持运输，即nZVI由可移动的胶体运输。在本研究中，使用长度为40cm、填充有多孔介质的柱进行柱试验，研究了活性炭胶体支持的nZVI（c-nZVI；d50 = 2.4μm）的传输特性。在不同的物理化学条件下（添加聚阴离子稳定剂以及pH值和离子强度的变化）将悬浮液泵入柱中。在添加稳定剂的玻璃珠中，观察到的最高突破为注入浓度的62%。添加单价和二价盐，例如超过0.5mM/L的CaCl2，会降低迁移性，而将pH值降至6以下会完全抑制迁移性。胶体尺寸和zeta电位的测量结果表明，在传输实验期间，平均粒径变化了一个数量级，zeta电位从-62mV增加到-80mV。然而，结果表明c-nZVI在现场条件下具有潜在的适用性。
