Abstract High-efficiency and good-selectivity extraction systems are very attractive in the solvent extraction process. A synergistic extraction of scandium (III) from a spent sulfuric acid solution of titanium dioxide production by using a mixture of bis-2-ethylhexyl phosphoric acid (D2EHPA, P204) and primary amine (N1923) has been proposed in this study. The effect of the molar fraction of N1923 in the mixed extractants on the extraction of scandium was studied and the synergistic enhancement coefficient R was calculated. The maximum synergistic coefficient was found to be 12.50 when the H2SO4 concentration was 0.5 mol·L−1 and the molar fraction of N1923 was 0.5. The synergistic extraction mechanism was also discussed. Appropriately 90% scandium could be stripped from the loaded organic phase in the synergistic extraction system when the nitric acid was 6 mol.L−1. The result of FT-IR spectra well verified the conclusion that the synergistic effect owed to the formation of hydrogen bond N H+···O P, causing a much easier dissociation of proton H of P204. Finally, after three-stage counter-current extraction and stripping, Sc2O5 product with a high purity of 90% was obtained from spent sulfuric acid solution by precipitation and calcination.

中文翻译：

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在二氧化钛生产中使用 D2EHPA 和伯胺 N1923 的协同溶剂萃取从废硫酸溶液中回收钪

摘要 高效、选择性好的萃取系统在溶剂萃取过程中非常有吸引力。本研究提出了使用双-2-乙基己基磷酸（D2EHPA，P2O4）和伯胺（N1923）的混合物从生产二氧化钛的废硫酸溶液中协同提取钪（III）。研究了混合萃取剂中N1923摩尔分数对钪萃取的影响，计算了协同增强系数R。当H2SO4 浓度为0.5 mol·L-1 和N1923 的摩尔分数为0.5 时，发现最大协同系数为12.50。还讨论了协同提取机制。当硝酸为6 mol.L-1时，协同萃取系统中90%的钪可以从负载的有机相中剥离出来。FT-IR光谱结果很好地验证了这一结论，即由于形成了氢键N H+...OP 的协同作用，使得P2O4的质子H更容易解离。最后，经过三级逆流萃取和汽提，从废硫酸溶液中沉淀和煅烧得到纯度高达90%的Sc2O5产品。