Race Marco
Dipartimento di Ingegneria Civile, Edile ed Ambientale, Università di Napoli Federico II, 80125 Napoli, Italy.
J Environ Manage. 2017 Dec 1;203(Pt 1):358-363. doi: 10.1016/j.jenvman.2017.08.013. Epub 2017 Aug 12.
This paper presents an innovative procedure for the recovery of SS-ethylenediamine-N,N'-disuccinic acid (EDDS) solution used for soil washing processes. The procedure is derived from that applied for the recovery of ethylenediamine-tetraacetic acid (EDTA), modifying and optimizing the choice of the chemical agents used for the protonation of the chelant, the exchange of the metals, and the final precipitation of the unwanted compounds. To select the reagents and test the proposed approach, an experimental study was conducted on real EDDS spent solutions, obtained washing a Cu and Zn real contaminated soil. According to the results obtained, the precipitation ranges from 30% to more than 90% for both Cu and Zn, depending on the adopted reagent sequence, and on the molar ratio between the salt and the chelant contained in the spent solution. Data were in agreement with chemical equilibrium predicted in ideal conditions. The recovered solutions had a reduced ability to remove the contaminants when applied in a new soil washing cycle (15% less for Cu and 30% less for Zn) because of the high concentration of alkaline metal ions required for the precipitation. At the same time, they were more biodegradable compared to non-treated solutions, confirming that EDDS-metal chelates may represent a threat for biological wastewater processes.
本文提出了一种用于回收土壤淋洗过程中使用的SS-乙二胺-N,N'-二琥珀酸（EDDS）溶液的创新方法。该方法源自用于回收乙二胺四乙酸（EDTA）的方法，对用于螯合剂质子化、金属交换以及不需要的化合物最终沉淀的化学试剂的选择进行了修改和优化。为了选择试剂并测试所提出的方法，对实际的EDDS废溶液进行了实验研究，这些废溶液是通过淋洗实际受铜和锌污染的土壤获得的。根据所得结果，铜和锌的沉淀率在30%至90%以上，这取决于所采用的试剂顺序以及废溶液中盐与螯合剂之间的摩尔比。数据与理想条件下预测的化学平衡一致。由于沉淀所需的碱金属离子浓度较高，回收的溶液在应用于新的土壤淋洗循环时去除污染物的能力降低（铜降低15%，锌降低30%）。同时，与未处理的溶液相比，它们的生物降解性更强，这证实了EDDS-金属螯合物可能对生物废水处理过程构成威胁。
