Department of Agricultural Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, ROC.
Department of Agricultural Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan, ROC.
Water Res. 2015 Apr 1;72:372-80. doi: 10.1016/j.watres.2014.12.038. Epub 2014 Dec 30.
In order to prevent the aggregation of nanoparticles (NPs), surface modification or the addition of a stabilizer are used for stabilization. However, the real reactivity of NPs is still unclear because of the surface coating. For different physical dispersion methods, the particle stabilization for nanoscale zerovalent iron (NZVI) particles and their reactivity are studied. The particle properties of different preparations and their reactivity toward one polychlorinated aromatic compound, pentachlorophenol (PCP), with different electrolytes are also evaluated. Ultrasonication (US) with magnetic stirring disperses NZVI and Pd/Fe NPs well in water and does not affect the surface redox property a lot under the operating conditions in this study. The well-suspended NZVI cannot dechlorinate PCP but adsorption removal is observed. Compared to shaking, which gives limited removal of PCP (about 43%), Pd/Fe NPs remove 81% and 93% of PCP from water in the US and the US/stirring systems, respectively, which demonstrates that a greater surface area is exposed because of effective dispersion of Pd/Fe NPs. As the Pd doping increases, the dechlorination kinetics of PCP is improved, which shows that a catalyst is needed. With US/stirring, chloride ions do not significantly affect the removal kinetics of PCP, but the removal efficiency increases in the presence of nitrate ions because PCP anions were adsorbed and coagulated by the greater amount of iron (hydro)oxides that are generated from the reduction of nitrate on Pd/Fe. However, bicarbonate ions significantly block the adsorption and reaction sites on the Pd/Fe NP surface with US/stirring. The US/stirring method can be used to evaluate the actual activity of NPs near the nanoscale. The use of Pd/Fe NPs with US/stirring removes PCP from water effectively, even in the presence of common anions expect a high concentration of bicarbonate.
为了防止纳米颗粒（NPs）的聚集，通常采用表面改性或添加稳定剂的方法进行稳定化处理。然而，由于表面涂层的存在，NPs 的真实反应活性仍不清楚。对于不同的物理分散方法，研究了纳米零价铁（NZVI）颗粒的颗粒稳定性及其反应活性。还评估了不同制备方法的颗粒性质及其对不同电解质中一种多氯代芳香族化合物五氯苯酚（PCP）的反应活性。在本研究的操作条件下，超声（US）结合磁场搅拌能很好地将 NZVI 和 Pd/Fe NPs 分散在水中，且对表面氧化还原性质的影响不大。良好悬浮的 NZVI 不能脱氯降解 PCP，但观察到吸附去除。与摇动相比，摇动对 PCP 的去除有限（约 43%），而在 US 和 US/搅拌系统中，Pd/Fe NPs 分别去除了 81%和 93%的 PCP，这表明由于 Pd/Fe NPs 的有效分散，暴露了更大的表面积。随着 Pd 掺杂量的增加，PCP 的脱氯动力学得到改善，这表明需要催化剂。在 US/搅拌条件下，氯离子对 PCP 的去除动力学没有显著影响，但在存在硝酸盐的情况下，去除效率会增加，因为来自硝酸盐在 Pd/Fe 上还原生成的更多铁（氢）氧化物会吸附和凝聚 PCP 阴离子。然而，碳酸氢根离子会显著阻塞 US/搅拌条件下 Pd/Fe NP 表面的吸附和反应位点。US/搅拌法可用于评估纳米尺度附近 NPs 的实际活性。使用 Pd/Fe NPs 并结合 US/搅拌可以有效地从水中去除 PCP，即使存在常见阴离子（除了高浓度的碳酸氢根离子）也是如此。
