College of Natural Resources and Environment , Northwest A&F University , Yangling , Shaanxi Province 712100 , PR China.
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China , Ministry of Agriculture , Yangling , Shaanxi 712100 , PR China.
Environ Sci Technol. 2018 Jul 17;52(14):7884-7891. doi: 10.1021/acs.est.8b02039. Epub 2018 Jul 5.
Strong complexation between heavy metals and organic complexing agents makes the heavy metals difficult to be removed by classical chemical precipitation. In this study, a novel decomplexation method was developed using discharge plasma oxidation, which was followed by alkaline precipitation to treat water containing heavy metal-organic complex, that is, Cu-ethylenediaminetetraacetic acid (Cu-EDTA). The decomplexation efficiency of Cu complex reached up to nearly 100% after 60 min's oxidation by discharge plasma, which was accompanied by 82.1% of total organic carbon removal and energy efficiency of 0.62 g kWh. Presence of free Cu favored Cu-EDTA decomplexation, whereas the presence of excessive EDTA depressed this process. Cu-EDTA decomplexation was mainly driven by the produced O, O, O, and •OH by discharge plasma. Cu-EDTA decomplexation process was characterized by UV-vis, ATR-FTIR, total organic carbon, and three-dimensional fluorescence diagnosis. The main intermediates including Cu-EDDA, Cu-IDA, Cu-NTA, small organic acids, NH, and NO were identified, accompanied by Cu releasing. The followed precipitation process removed 78.1% of Cu, and Cu-associated precipitates included CuCO, CuCO(OH), CuO, and Cu(OH). A possible pathway of Cu complex decomplexation and Cu removal in such a system was proposed.
重金属与有机络合剂之间的强络合作用使得重金属难以通过经典的化学沉淀去除。在这项研究中，采用放电等离子体氧化法开发了一种新型的解络合方法，随后通过碱性沉淀处理含有重金属-有机络合物的水，即 Cu-乙二胺四乙酸（Cu-EDTA）。经过 60 分钟的放电等离子体氧化，Cu 络合物的解络合效率达到近 100%，同时总有机碳去除率达到 82.1%，能量效率为 0.62 g kWh。游离 Cu 的存在有利于 Cu-EDTA 的解络合，而过量 EDTA 的存在则抑制了这一过程。Cu-EDTA 的解络合主要是由放电等离子体产生的 O、O、O 和 •OH 驱动的。Cu-EDTA 解络合过程通过 UV-vis、ATR-FTIR、总有机碳和三维荧光诊断进行了表征。确定了主要中间体包括 Cu-EDDA、Cu-IDA、Cu-NTA、小分子有机酸、NH 和 NO，同时伴随着 Cu 的释放。随后的沉淀过程去除了 78.1%的 Cu，Cu 相关的沉淀物包括 CuCO、CuCO(OH)、CuO 和 Cu(OH)。提出了该系统中 Cu 络合物解络合和 Cu 去除的可能途径。
