Immobilization of soluble U(VI) from simulated wastewater into a stable mineral: V2O5-Induced crystallization of uvanite for uranium remediation.

The extraction of uranium (U) from wastewater is of vital importance for ensuring the sustainable and safe development of nuclear energy, as it addresses both environmental protection and resource recycling. Vanadium (V) and its compounds are extensively employed in iron and steel manufacturing, and their utility in pollutant remediation further promotes the circular use of V-bearing materials. However, studies on utilizing inexpensive and readily available vanadium oxides (e.g., V2O5) for the treatment of highly acidic uranium-containing wastewater remain scarce. This study investigated the effectiveness of V2O5 in removing U(VI) and immobilizing it into crystalline uranyl vanadates, providing the first confirmation of the feasibility of using V2O5 for uranium elimination and capture. The results indicate that V2O5 exhibits excellent extraction capacity and selectivity for uranyl ions in contaminated solutions, achieving a U(VI) extraction efficiency exceeding 97 % even under highly acidic conditions (e.g., pH = 2.0). Adsorption equilibrium was attained within 240 min, and kinetic studies combined with model fitting indicated that the process was governed by both intra-particle diffusion and chemical adsorption mechanisms. It was discovered that the captured U(VI) was ultimately incorporated into a stable crystalline phase, identified as uvanite (U2V6O21·15H2O), through a coprecipitation pathway, revealing a novel crystallization mechanism. The overall immobilization process was attributed to the synergistic effects of chemical adsorption and coprecipitation. These findings support the development of vanadium oxide-based technologies for U(VI) purification and recovery from complex wastewater.