Preparation of Highly Pure Vanadyl Sulfate from Sulfate Solutions Containing Impurities of Iron and Aluminum by Solvent Extraction Using EHEHPA

Abstract

Abstract:The preparation of highly pure vanadyl sulfate from sulfate solutions containing impurities of iron and aluminumwas investigated by solvent extraction with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (EHEHPA) and tri-n-butyl phosphate (TBP) as the phase modifier. The extraction and stripping conditions of vanadium (IV) and its separation from iron and aluminum were optimized. Under the optimal extraction conditions, the extraction of vanadium (IV) and iron were 68% and 53%, respectively, while only 2% aluminum was extracted in a single contact, suggesting good separation of vanadium (IV) from aluminum. Sulfuric acid solution was used for the stripping. Nearly 100% vanadium (IV) and 95% aluminum were stripped, while only 10% iron was stripped under the optimal stripping conditions in a single contact, suggesting good separation of vanadium (IV) from iron. After five stages of extraction and stripping, highly pure vanadyl sulfate containing 76.5 g/L V (IV) with the impurities of 12 mg/L Fe and 10 mg/L Al was obtained, which is suitable for the electrolyte of a vanadium redox flow battery. Organic solution was well regenerated after stripping by oxalic acid solution to remove the remaining iron. The mechanism of vanadium (IV) extraction using EHEHPA was also discussed based on the Fourier transform infrared spectroscopy (FT-IR) analysis.

Functional materials for aqueous redox flow batteries: merits and applications

“…38 The preparation of vanadium electrolyte presents a major challenge in the development and commercialization of VRFBs, mainly due to the high cost of commercial vanadium species. Scholars have developed various methods to reduce the cost of electrolytes, including chemical reduction, 39 electrolysis, 40 solvent extraction, 41 and ion exchange (Fig. 4d).…”

Valuable Metal Recycling

“…Li et al [14] developed a recycling process for preparing highly pure vanadyl sulfate from iron and aluminum impurities. Vanadium and iron ions was selectively extracted by solvent extraction with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (EHEHPA) and tri-n-butyl phosphate (TBP) as the phase modifier; vanadium ion was selectively recovered by stripping with sulfuric acid solution.…”

Novel Process to Prepare a Vanadium Electrolyte from a Calcification Roasting–Acid Leaching Solution of Vanadium Slag

“…pentoxide. As shown in Table S1, − vanadium electrolytes are prepared by solvent extraction. In particular, an electrolyte with a vanadium concentration of 76.52 g·L –1 can be prepared by solvent extraction using sodium polyvanadate precipitated wastewater as a raw material, and the recovery rate can reach 98.74%.…”