Di Palma L, Ferrantelli P, Merli C, Biancifiori F
Dipartimento di Ingegneria Chimica, dei Materiali, delle Materie Prime, Metallurgia Università di Roma La Sapienza, via Eudossiana 18, 00184, Rome, Italy.
J Hazard Mater. 2003 Oct 1;103(1-2):153-68. doi: 10.1016/s0304-3894(03)00268-1.
This work studies the effectiveness of a process proposed for the recovery of ethylenediaminetetraacetic acid (EDTA) and metal precipitation from soil flushing solutions. Two series of experimental tests were carried out on two samples of a soil artificially contaminated with copper or lead. The metals were extracted from the soil by flushing with a 0.05 M aqueous solution of EDTA sodium salt (E-Na(2)). Cu or Pb extraction efficiencies of about 95 and 98% were observed, respectively. The two extracted solutions were then treated to obtain EDTA recovery and metal precipitation from the aqueous solution. EDTA recovery was achieved in two steps. An initial evaporation treatment lead to reduce the solution volume by about 75%. This was followed by the acidification of the residue solution, which precipitated more than 93% of the used EDTA. The precipitated EDTA was removed by filtration, and was suitable for reuse after adding an alkaline agent. Metal precipitation from the filtered solution was performed using two different methods: an almost total (99.5%) Pb precipitation in alkaline conditions was achieved after complex destabilization through the sequential addition of ferric ions and sodium phosphate, while 93.6% copper precipitation was achieved with ferrous sulfate as a destabilization agent.
本研究考察了一种从土壤冲洗液中回收乙二胺四乙酸（EDTA）并沉淀金属的工艺的有效性。对两份分别被铜或铅人工污染的土壤样品进行了两组实验测试。通过用0.05M的乙二胺四乙酸钠盐（E-Na(2)）水溶液冲洗从土壤中提取金属。分别观察到铜和铅的提取效率约为95%和98%。然后对两种提取液进行处理，以从水溶液中回收EDTA并沉淀金属。EDTA的回收分两步进行。初步蒸发处理使溶液体积减少约75%。随后对残留溶液进行酸化，使超过93%的用过的EDTA沉淀。通过过滤除去沉淀的EDTA，添加碱性试剂后可重复使用。使用两种不同方法从过滤后的溶液中沉淀金属：通过依次添加铁离子和磷酸钠使络合物失稳后，在碱性条件下实现了几乎完全（99.5%）的铅沉淀，而使用硫酸亚铁作为失稳剂实现了93.6%的铜沉淀。
