The remobilization of metals from iron oxides and sediments by metal-EDTA complexes
The remobilization of metals from iron oxides and sediments by metal-EDTA complexes
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DOI：
10.1023/a:1005296312509
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发表时间：
2001-01-01
影响因子：
2.9
通讯作者：
Krüger, HG
中科院分区：
文献类型：
--
作者：
Nowack, B;Kari, FG;Krüger, HG
EDTA 等合成螯合剂可与重金属形成牢固的络合物，因此具有从沉积物和含水层中重新激活金属的潜力。在天然水中，EDTA 几乎完全以金属络合物的形式存在。因此，金属的再活化始终是金属-金属-EDTA交换反应。据我们所知，我们首次研究了不同金属-EDTA 络合物对合成铁氧化物表面和河流沉积物中金属的再活化作用。金属交换如下：MeEDTA(溶解) + Me-吸附* --> Me*EDTA(溶解) + Me-吸附 针铁矿中 Zn2+ 的再活化速率顺序为 CaEDTA > Fe(III)EDTA，反映了 Fe(III)EDTA 的缓慢交换反应。对于针铁矿中 Pb2+ 的再活化，速率为 Fe(III)EDTA > CaEDTA > ZnEDTA。令人惊讶的是，Fe(III)EDTA 的交换速率最快。由于 Pb2+ 的吸附力非常强，因此在 pH 8 时，水合氧化铁中只能对 Pb2+ 进行非常有限的再活化。发现天然河流沉积物中 Zn2+ 的再活化顺序为 CaEDTA > CuEDTA > Fe(III)EDTA。 Fe(III)EDTA 对 Zn2+ 的再活化率仅为 CaEDTA 的 12%，说明 EDTA 形态对于评估再活化的重要性。
Synthetic chelating agents such as EDTA form strong complexes with heavy metals and therefore have the potential to remobilize metals from sediments and aquifers. In natural waters EDTA is present almost exclusively in the form of metal-complexes. Therefore, remobilization of metals is always a metal-metal-EDTA exchange reaction. We have investigated, to our knowledge for the first time, the remobilization of metals from the surface of synthetic iron oxides and from a river sediment by different metal-EDTA complexes. The metals are exchanged as follows:MeEDTA(dissolved) + Me-adsorbed* --> Me*EDTA(dissolved) + Me-adsorbedThe order of the remobilization rate of Zn2+ from goethite is CaEDTA > Fe(III)EDTA, reflecting the slow exchange reaction of Fe(III)EDTA. For the remobilization of Pb2+ from goethite, the rate was found to be Fe(III)EDTA > CaEDTA > ZnEDTA. Here, Fe(III)EDTA has surprisingly the fastest exchange rate. Only very limited remobilization of Pb2+ is possible from hydrous ferric oxide at pH 8 due to the very strong adsorption of Pb2+. The order of remobilization of Zn2+ from a natural river sediment was found to be CaEDTA > CuEDTA > Fe(III)EDTA. The remobilization rate of Zn2+ with Fe(III)EDTA is only 12% of the rate with CaEDTA, illustrating the importance of EDTA speciation for assessing remobilization.