A Sustainable Technique to Prepare High-Purity Vanadium Pentoxide via Purification with Low Ammonium Consumption

The general preparation method for V O is ammonium salt vanadium precipitation, which inevitably produces large amounts of ammonia nitrogen wastewater. In this paper, we propose an environmentally friendly method for preparing high-purity V O with low ammonium consumption. The purity of the V O product reaches more than 99% while reducing the level of ammonium consumption. The vanadium precipitation efficiency reaches 99.23% and the V O purity of the product reaches 99.05% under the following conditions: precipitation time of 1.5 h, precipitation temperature of 98 °C, initial precipitation pH of 2, ammonium addition coefficient of 2, purification time of 5 min with purification performed twice, purification temperature of 65 °C. In this study, compared with the use of ammonia spirit for vanadium precipitation and ammonium salt vanadium precipitation, the ammonia consumption levels are reduced by 79.80% and 80.00%, and the purity levels are increased by 0.70% and 1.01%, respectively. The compositions of the precipitated (NaV O ∙xH O) and purified ((NH ) V O ·1.5H O) hydrolysis products are characterized via XRD. The TGA results show that NaV O ∙xH O contains 1.5 times the amount of crystal water. The FTIR results explain that the two V O layers are combined end-to-end to form a V O layer. The change of the product image indicates that the purification process includes three stages. Firstly, heating and NH attack expand the V O layer. NH4 diffuses more easily into the V O layer. Secondly, NH destroys the electrostatic interaction between Na with the V O layer and replacing Na . Finally, V O is polymerized into V O to keep the crystal structure stable.