Extraction and recovery of V(V) from citrate leachate of spent catalyst containing impurities (Mg and Fe) using tricapryl methyl ammonium chloride

Abstract

A systematic investigation was carried out for the selective extraction and recovery of vanadium from a citric acid-mediated leach liquor of spent catalyst using a mixture of Aliquat 336 and 2-Octanol. Prior to extraction, iron was efficiently removed at pHe 4.0 via slaked lime precipitation. Extraction equilibrium studies indicated that vanadium was predominantly extracted as the [VO(C6H5O7)] 2- anionic complex by Tricarpyl methyl Ammonium Chloride (Aliquat 336). The association of 2 mol of aliquat 336 was confirmed from the slope analysis method with extraction of vanadium from citrate media as [ (CH 3 R 3 N) 2 ] VO(C6H5O7) ] (org) . Vanadium extraction was quantitative under conditions of pH 6.0 ensuring no co-extraction of magnesium. Extraction isotherm examined using 0.6 M Aliquat 336 + 10% (v/v) 2-octanol at A: O = 8:1 in two stages leading to attaining 5 folds enrichment of vanadium during extraction. FTIR analysis confirmed the successful coordination of vanadium in the organic phase. Stripping of vanadium using NaOH at an aqueous-to-organic (A:O) ratio of 1:5 yielded a concentrated strip solution containing 47.2 g/L vanadium, representing almost eightfold enrichment compared to the initial leachate. Final precipitation and calcination of the strip solution produced high-purity V2O5, confirmed by XRD analysis. This study demonstrates a clean, efficient, and environmentally benign method for the selective recovery of vanadium from spent catalyst leachates using ionic liquid-based solvent extraction.