Purification of vanadium products by removal of chromium compounds, especially at high pH, remains a challenging task. In this contribution, purification of sodium vanadate solutions by selective solvent extraction of Cr(VI) from strong alkaline aqueous solution (initial pH 12 and above) was investigated, and the mechanisms governing the selectivity of quaternary ammonium salt Aliquat 336 were studied and discussed in detail. The influence of critical technological parameters including pH of the feed solution, added modifier, diluent, and contact time were examined and analyzed systematically. The experiments reveal a high extraction power for Cr(IV) using Aliquat 336 in the presence of TBP, realizing no extraction of V(V) under optimized condition. Stripping of Cr(VI) from the loaded organic phase was furthermore evaluated. The present work highlights a new approach to separate Cr(VI) from strong alkaline solution with a high degree of selectivity which enables the achievement of a high purity sodium vanadate.

通过去除铬化合物来净化钒产品，尤其是在高pH条件下，仍然是一项艰巨的任务。在这一贡献中，研究了通过从强碱性水溶液（初始pH 12及以上）中选择性萃取Cr（VI）溶剂纯化钒酸钠溶液的方法，并研究了控制季铵盐Aliquat 336选择性的机理。详情。系统地检查和分析了关键技术参数的影响，包括进料溶液的pH，添加的改性剂，稀释剂和接触时间。实验表明，在存在TBP的情况下，使用Aliquat 336可对Cr（IV）进行高萃取，从而在优化条件下也不会萃取V（V）。此外，还评估了负载有机相中Cr（VI）的汽提。