An eco-friendly vanadium precipitation method through solution-phase hydrogen reduction with nickel catalysis

Background: The traditional process of vanadium precipitation would produce a large amount of ammonia nitrogen wastewater, which restricts its sustainable development. Differently, the SpHR (solution-phase hydrogen reduction) process is without carbon and ammonia emissions and has advantages of eco friendliness, lower energy consumption, higher productivity, and economical feasibility. Methods: The SpHR technology was introduced into vanadium precipitation process in this research. Nickel (Ni) powder and polyethylene glycol were used as catalyst and dispersant, respectively. Two-stage magnetic separation was adopted for separating Ni over V2O3. Findings: The vanadium precipitation efficiency can reach 99.61% under optimum conditions of Ni dosage of 20 g/L, temperature of 250 C, pH value of 5.5, vanadium concentration of 0.5 mol/L, H-2 partial pressure of 4 MPa. The V2O3 purity of precipitate can stabilize at 99.11% after three-cycle SpHR. The activation energy of SpHR of vanadium precipitation can be calculated as 140.09 kJ/mol, which marks that the SpHR process is controlled by chemical reaction. The H-2 is cracked by elemental Ni in the range of 250 C-300 C, and low activation energy of H-2 desorption is 9.6994 kJ/mol, which ensures that H-2 has sufficient reducing activity during SpHR. (c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

This research introduced the SpHR technology into the vanadium precipitation process, achieving a high efficiency of vanadium precipitation. Under optimal conditions, the vanadium precipitation efficiency reached 99.61%, and the purity of the precipitate stabilized at 99.11% after three cycles of SpHR. The SpHR process of vanadium precipitation is controlled by chemical reaction, and H-2 exhibits sufficient reducing activity.