Removing trace chromium from high concentration vanadium solution by photoreduction deposition with Ti–Zr solid solution

• Published in: Separation and purification technology 2022-06, Vol.290, p.120855, Article 120855
• Main Authors: He, Kunpeng, Chen, Pingting, Yuan, Biao, Sun, Fujin, He, Jian, Wu, Pan, Liu, Changjun, Jiang, Wei
• Format: Article
• Language: English
• Subjects: Deep purification; Photocatalytic reduction process; Ti–Zr solid solution; Trace chromium; Ultrahigh-purity vanadium
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2022.120855

•Cr(VI) removal mechanism based on competitive adsorption-photoreduction-deposition.•Separating trace chromium from massy vanadium down to 0.001 wt% by photoreduction.•Using a high-efficiency and low-cost photoreduction technique to purify V2O5.•Constructing an effective purification technique for producing ultra-high purity vanadium.•Chemical behavior of V and Cr on a photocatalyst was simulated. The preparation of ultrahigh-purity vanadium (>99.99 wt%) requires the removal of trace amounts of chromium, but economical vanadium purification is difficult to achieve using crude vanadium mother liquors (>98 wt%) because of the similar properties of V(V) and Cr(IV) ions. In this study, a Ti–Zr solid solution was used for the deep purification of high-concentration ammonium polyvanadate by removing trace chromium using photocatalytic reduction process. The results show that V(V) and Cr(VI) are competitively adsorbed and photoreduced, but V(V) adsorption is preferred and occurs more rapidly than that of Cr(VI). However, after the photoreduction product of V(V), V(IV) is desorbed, whereas after that of Cr(VI), Cr(III) is deposited on the photocatalyst, achieving the separation of vanadium and chromium. The 2 h removal efficiency of chromium exceeds 80%, and the chromium content in the obtained vanadium is less than 0.04 wt%. After precipitation, the chromium content in the obtained ammonium metavanadate is less than 0.001 wt%, and the purity of the final V2O5 product exceeds 99.99%, which meets the requirement for ultrahigh-purity vanadium products. The used photocatalyst can be regenerated and reused with stable performance. This work provides a reference method for ultrahigh-purity vanadium production and an example of the industrial application of the photoreduction process.