Recovery of High-Purity Vanadium from Aqueous Solutions by Reusable Primary Amines N1923 Associated with Semiquantitative Understanding of Vanadium Species

The recovery of high-purity vanadium has attracted significant attention regarding both sustainability and environmental protection necessities. However, insufficient understanding of vanadium species in aqueous solution constrains further optimization of the vanadium recovery process. Here, a closed-loop technical route (extraction and stripping) was realized to recover high-purity vanadium products by in situ monitoring/controlling vanadium species. The evolution of vanadium species in the extraction reaction was semiquantitatively visualized by the system combined with annular centrifugal contactors (ACCs) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), while the active (V₄ and V₁₀ species) and nonactive (H₂VO₄^–) vanadium species were identified. In the stripping process, the behaviors of vanadium species have been described, which affected the morphology of recycled NH₄VO₃ products. As a result, the transformation pathway of vanadium species in the whole recovery process was performed. Under deep studies of vanadium speciation, pilot-scale experiments have been carried out using actual leaching solution, and high-purity V₂O₅ products (99.9%) were obtained.