| Popis: |
Transition metal vanadates have shown potential in applications as sensors, in photocatalysis, and recently, because of their high theoretical capacity, safety, easy preparation, and low cost, as electrode materials for primary and rechargeable batteries. Motivated by these relevant applications, much research work has been done on the synthesis and electrochemical studies of various 1D transition metal vanadates. Metal vanadates are normally synthesized by hydrothermal methods at high temperatures and pressures, making the synthesis expensive, and the control of the microstructure and composition difficult to achieve. Vanadium can currently be found in the slag by-products of certain steel production processes, and the development of hydrometallurgical processes for the recovery and purification is relevant, mostly from alkaline media. Various methods are being investigated for separation of the metal value from alkaline leach feeds, including solvent extraction. In case of the recovery of vanadium an interesting modification of the conventional solvent extraction process is the addition of a crystallization operation (precipitation stripping). In this work, the extraction was carried out using an Aliquat 336 solution in n-octanol/kerosene as extractant. Precipitation stripping was carried out using several metal salts dissolved in a concentrated chloride solution. For some experiments, polyvinylpyrrolidone was used as stabilizer in order to avoid agglomeration and to control growth. The structural characteristics of the crystallized products were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable vanadium compounds. |
