Simultaneous extraction of Cr(VI) and Cu(II) from humic acid with new synthesized EDTA derivatives.
Simultaneous extraction of Cr(VI) and Cu(II) from humic acid with new synthesized EDTA derivatives.
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DOI：
10.1016/j.chemosphere.2012.04.003
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发表时间：
2012-07
期刊：
影响因子：
8.8
通讯作者：
Tao Zhang;Yingxin Wu;Xiong-fei Huang;Jun‐Min Liu;Bing Xia;Weihua Zhang;R. Qiu
中科院分区：
文献类型：
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作者：
Tao Zhang;Yingxin Wu;Xiong-fei Huang;Jun‐Min Liu;Bing Xia;Weihua Zhang;R. Qiu
土壤清洗是去除金属污染物的为数不多的永久性处理选择之一。乙二胺四乙酸及其盐类(EDTA)在去除阳离子金属方面非常有效，已在全球范围内得到应用。然而，对于阴离子金属污染物或与土壤有机质结合的金属来说，它是无效的。由于阳离子和阴离子金属污染物的性质不同，通过土壤清洗同时去除它们是困难的。本研究评估了两种合成的EDTA衍生物，C6HEDTA(2，2′-((2-((carboxymethyl)(2-(hexanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic酸)和C12HEDTA(2，2‘-(2-(羧甲基)(2-(dodecanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic酸)，由亲水性多羧酸部分和带有单烷基酯的疏水部分组成的洗涤过程的可能性。研究了C6HEDTA和C12HEDTA作为萃取剂对含氧阴离子铬(VI)和阳离子铜(II)的萃取效果。结果表明，C6HEDTA和C12HEDTA均能同时萃取腐植酸中的铬(VI)和铜(II)。然而，C6HEDTA对六价铬的吸附效果较差，可能是因为它不像C12HEDTA那样具有增加腐植酸溶解度的表面活性。铬(VI)的萃取主要归因于表面张力的降低和有机质的溶解能力的提高。铜(II)的萃取是由于胡敏酸对铜(II)的络合作用和增溶作用所致。结果表明，C12HEDTA的亲水性聚羧酸部分对阳离子起螯合作用，而单烷基酯基团则具有提高腐植酸溶解度的表面活性。
Soil washing is one of the few permanent treatment alternatives for removing metal contaminants. Ethylenediaminetetraacetic acid and its salts (EDTA) is very effective at removing cationic metals and has been utilized globally. However it is ineffective for anionic metal contaminants or metals bound to soil organic matter. The simultaneous removal of cationic and anionic metal contaminants by soil washing is difficult due to differences in their properties. The present study evaluated the potential of a washing process using two synthesized EDTA-derivatives, C6HEDTA (2,2′-((2-((carboxymethyl)(2-(hexanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid) and C12HEDTA (2,2′-((2-((carboxymethyl) (2-(dodecanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid), which consist of a hydrophilic polycarboxylic moiety and a hydrophobic moiety with a monoalkyl ester group. A series of equilibrium batch experiments at room temperature were conducted to investigate the efficacy of C6HEDTA and C12HEDTA as extractants for both oxyanion Cr(VI) and cationic Cu(II). Results showed that either C6HEDTA or C12HEDTA can extract both Cr(VI) and Cu(II) from humic acid simultaneously. However, C6HEDTA was less effective for Cr(VI) probably because it has no surface activities to increase solubility of humic acid, like C12HEDTA. Extraction of Cr(VI) was mainly attributed to the decreased surface tension and enhanced solubility of organic matter. Extraction of Cu(II) was attributed to both the Cu(II) chelation and enhanced solubility of humic acid. It was demonstrated that the hydrophilic polycarboxylic moiety of C12HEDTA chelates cations while the monoalkyl ester group produces surface active properties that enhance the solubility of humic acid.