Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, 30100 Agrinio, Greece.
J Colloid Interface Sci. 2010 Mar 1;343(1):374-80. doi: 10.1016/j.jcis.2009.11.029. Epub 2009 Nov 22.
A novel hybrid MCM-41-based material was synthesized by incorporation of AEDTC [N-(2-aminoethyl)dithiocarbamate] in the MCM-41 pores. The derived MCM-41 x AEDTC material possesses high AEDTC loading 35% [w:w], and a well-defined array of regular mesopores with a specific surface area of 632 m(2)/g. Heavy metal, Cd, Pb, Cu, and Zn, uptake was studied in detail at physiological pH values 6-8, by a combination of analytical and electron paramagnetic resonance (EPR) spectroscopic techniques. The analytical data show a significant improvement, i.e., 200-500%, for Pb, Cu, and Zn uptake by the MCM-41 x AEDTC hybrid vs the unmodified MCM-41. In contrast, Cd shows an exceptional behavior: (a) Cd uptake by MCM-41 x AEDTC is very low. (b) Competitive metal uptake experiments reveal that Cd ions cause a characteristic inhibition of Cu or Pb uptake by the MCM-41 x AEDTC while Cd binding itself always remained low. The present findings are analyzed by a combination of surface complexation modeling and EPR spectroscopy. Accordingly, in the MCM-41 x AEDTC the sulfur atoms of AEDTC provide strong binding sites for metal binding, with a stoichiometry [S(AEDTC)]:[Metal] = 1:1. Cd inhibits accessibility of Cu or Pb ions in the AEDTC sites.
一种新型的基于 MCM-41 的混合材料是通过在 MCM-41 孔中掺入 AEDTC[N-(2-氨乙基)二硫代氨基甲酸盐]合成的。所得的 MCM-41 x AEDTC 材料具有高的 AEDTC 负载量 35%[w:w]，以及具有 632 m(2)/g 的比表面积的规则介孔的良好排列。在生理 pH 值 6-8 下，通过分析和电子顺磁共振（EPR）光谱技术的组合，详细研究了重金属 Cd、Pb、Cu 和 Zn 的摄取。分析数据表明，与未改性的 MCM-41 相比，Pb、Cu 和 Zn 的摄取量有显著提高，即 200-500%。相比之下，Cd 表现出异常的行为：（a）Cd 被 MCM-41 x AEDTC 的摄取量非常低。（b）竞争性金属摄取实验表明，Cd 离子导致 MCM-41 x AEDTC 中 Cu 或 Pb 的摄取出现特征性抑制，而 Cd 结合本身始终保持低水平。本研究结果通过表面络合模型和 EPR 光谱学的组合进行了分析。因此，在 MCM-41 x AEDTC 中，AEDTC 的硫原子提供了金属结合的强结合位点，其化学计量比[S(AEDTC)]：[金属] = 1:1。Cd 抑制了 AEDTC 位点中 Cu 或 Pb 离子的可及性。
