In this study, the removal mechanisms of sulfidated nanoscale zero-valent iron (S-nZVI) toward EDTA-chelated Cd^II (Cd^II-EDTA) and the detailed effects of some critical factors on Cd^II-EDTA removal by S-nZVI were systematically investigated. The results showed that the removal capacity of S-nZVI toward Cd^II-EDTA within 90 min of reaction was 746.6 mg/g (when the initial concentration of Cd^II-EDTA, the dosage of S-nZVI, and the initial solution pH were 300.0 mg Cd^II/L, 0.3 g/L, and 2.6, respectively), which was 6.2 and 2.5 times higher than that of nZVI and Na₂S, respectively, indicating that Fe and S had coupled effect on Cd^II-EDTA removal. The removal mechanisms of Cd^II-EDTA by S-nZVI consisted of two-step replacement reactions. In brief, Fe^III generated from the corrosion of S-nZVI firstly replaced the Cd^II in Cd^II-EDTA, and then the decomplexed Cd^II ions were immobilized by occurring the second-step replacement reaction with FeS in S-nZVI and forming CdS phase. Batch experiment results indicated that the removal of Cd^II-EDTA by S-nZVI decreased as the initial Cd^II-EDTA concentration increased and S-nZVI dosage decreased. Under the same S-nZVI dosage (0.3 g/L) and initial Cd^II-EDTA concentration (300.0 mg Cd^II/L), the acidic initial pH (pH₀ = 2.6) was favorable for the removal of Cd^II-EDTA. This study demonstrated that S-nZVI could be a viable choice for the Cd^II-EDTA-contaminated wastewater treatment.

在本研究中，硫化纳米级零价铁 (S-nZVI) 对 EDTA 螯合的 Cd ^II (Cd ^II -EDTA)的去除机制以及一些关键因素对S-nZVI 去除Cd ^II -EDTA的详细影响是系统地调查。结果表明，S-nZVI在反应90 min内对Cd ^II -EDTA的去除能力为746.6 mg/g（当Cd ^II -EDTA的初始浓度、S-nZVI用量和初始溶液pH为300.0 mg Cd ^II /L、0.3 g/L 和 2.6)，分别是 nZVI 和 Na ₂ S 的6.2 倍和 2.5 倍，表明 Fe 和 S 对 Cd ^II具有耦合作用-EDTA去除。S-nZVI对 Cd ^II -EDTA的去除机制包括两步置换反应。简而言之，S-nZVI 腐蚀产生的Fe ^III首先取代了 Cd ^II -EDTA中的 Cd ^II，然后通过与 S-nZVI 中的 FeS 发生第二步置换反应并形成 CdS 固定了解络的Cd ^II离子阶段。批量实验结果表明，随着初始Cd ^II -EDTA浓度的增加和S-nZVI用量的减少，S-nZVI对Cd ^II -EDTA的去除率降低。在相同的 S-nZVI 剂量 (0.3 g/L) 和初始 Cd ^II -EDTA 浓度（300.0 mg Cd ^II/L)，酸性初始 pH (pH ₀  = 2.6) 有利于去除 Cd ^II -EDTA。该研究表明，S-nZVI 可能是 Cd ^II -EDTA 污染废水处理的可行选择。