Abstract This work presents a study of the separation and recovery of metal elements, through a multi-step protocol based on solvent extraction, stripping and chemical precipitation processes. The waste leachate was produced during the treatment of the mixed solid waste from the decommissioning of a coal-fired power plant. The organophosphorus acid, di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated as organic extracting agent during the solvent extraction (Step 1). A factorial design with three levels for the organic phase/aqueous phase ratio (O/W), DEHPA concentration and contact time were carried out and a prediction model obtained using a neural-fuzzy approach. Optimized extraction values for Ti (93.4 %), (V) 94.6 % and (Zn) 89.8 % were obtained using 60 min of contact time, a DEHPA concentration of 0.5 M and O/W ratio of 4. Stripping tests were performed using HCl, H2SO4, NaOH and KOH as stripping agents. The stripping step (step 2) showed optimum results (82 % of Zn and 31 % of V) using 1 M H2SO4 solution as stripping agent. A selective precipitation step (step 3) allowed the final separation of metals in aqueous solutions produced in Step 1 and 2. The results showed that an effective separation of Mn and Ni could be carried out at pH 9, while the best separation results for the solution obtained during the stripping step, which contains V and Ti, was obtained at pH 12.

中文翻译：

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迈向有效的多步分离协议，以从废物渗滤液中回收金属成分

摘要 这项工作通过基于溶剂萃取、汽提和化学沉淀过程的多步骤方案，对金属元素的分离和回收进行了研究。垃圾渗滤液是在处理燃煤电厂退役的混合固体废物过程中产生的。在溶剂萃取（步骤 1）期间，有机磷酸、二-（2-乙基己基）磷酸 (DEHPA) 作为有机萃取剂进行了研究。对有机相/水相比 (O/W)、DEHPA 浓度和接触时间进行了三个水平的因子设计，并使用神经模糊方法获得了预测模型。使用 60 分钟的接触时间、0.5 M 的 DEHPA 浓度和 4 的 O/W 比获得 Ti (93.4 %)、(V) 94.6 % 和 (Zn) 89.8 % 的优化萃取值。使用 HCl、H2SO4、NaOH 和 KOH 作为汽提剂进行汽提测试。汽提步骤（步骤 2）使用 1 M H2SO4 溶液作为汽提剂显示出最佳结果（82% 的 Zn 和 31% 的 V）。选择性沉淀步骤（步骤 3）允许最终分离步骤 1 和 2 中产生的水溶液中的金属。结果表明，Mn 和 Ni 的有效分离可以在 pH 9 下进行，而对于在汽提步骤中获得的溶液含有 V 和 Ti，在 pH 值为 12 时获得。