Abstract The chromium-containing industrial wastewater, as a type of common widespread hazardous waste, causes many environmental issues. This study aimed to develop a novel amide as extractant and evaluate its recovery of chromium(VI) in aqueous solutions. Comparing nine amides with different alkyl groups and six diluents with different polarity, 40% (v/v) C14H29NO and 60% (v/v) D80 were found to be the best composition of extractant solution. Meanwhile, batch-wise experiments were performed to investigate the influence of various operating variables on the extracting, scrubbing and stripping behavior. The results demonstrated that 99.67% chromium could be extracted after six-stage countercurrent extraction, almost all impurity ions such as Na, V, Al and Mg could be removed from the loaded organic phase after three-stage cross-current scrubbing and 95.72% chromium could be stripped after six-stage countercurrent stripping respectively under the optimum conditions. The Cr2O3 product with 99.01% purity was obtained and total chromium recovery from the chromium(VI) waste solution was 95.40%. Chromic and dichromate acid were extracted by forming neutral and ion association complexation with amide C14H29NO, respectively. Finally, thermodynamics and the possible structure of chromium extraction compounds were elaborated. It is believed that this established method is promising way for the treatment of chromium-containing industrial wastewater.

中文翻译：

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酰胺溶剂萃取法回收废水中的六价铬

摘要 含铬工业废水作为一种普遍存在的危险废物，引起了许多环境问题。本研究旨在开发一种新型酰胺作为萃取剂并评估其在水溶液中回收六价铬。比较 9 种不同烷基的酰胺和 6 种不同极性的稀释剂，发现 40% (v/v) C14H29NO 和 60% (v/v) D80 是萃取剂溶液的最佳组成。同时，进行分批实验以研究各种操作变量对萃取、洗涤和汽提行为的影响。结果表明，六级逆流萃取后可萃取99.67%的铬，几乎所有的杂质离子如Na、V、在最佳条件下，经过三级错流洗涤后，负载的有机相中的铝和镁可以被去除，六级逆流洗涤后可以分别脱除95.72%的铬。得到纯度为 99.01% 的 Cr2O3 产品，从六价铬废液中总铬回收率为 95.40%。通过分别与酰胺 C14H29NO 形成中性和离子缔合络合来提取铬酸和重铬酸。最后，详细阐述了铬萃取化合物的热力学和可能的结构。相信这种已建立的方法是处理含铬工业废水的有前途的方法。获得了 01% 的纯度，从铬 (VI) 废液中回收的总铬为 95.40%。通过分别与酰胺 C14H29NO 形成中性和离子缔合络合来提取铬酸和重铬酸。最后，详细阐述了铬萃取化合物的热力学和可能的结构。相信这种已建立的方法是处理含铬工业废水的有前途的方法。获得了 01% 的纯度，从铬 (VI) 废液中回收的总铬为 95.40%。通过分别与酰胺 C14H29NO 形成中性和离子缔合络合来提取铬酸和重铬酸。最后，详细阐述了铬萃取化合物的热力学和可能的结构。相信这种已建立的方法是处理含铬工业废水的有前途的方法。