Differential adsorption of vanadium(V) and tungsten(W) on ion exchange resins: A novel approach for separation and recovery of spent catalyst leachate

• Published in: Journal of cleaner production 2023-11, Vol.426, p.139157, Article 139157
• Main Authors: Hong, Hye-Jin, Yoo, Heeji, Jeon, Jong Hyuk, Kim, Hee Seo, Lee, Jin-Yong
• Format: Article
• Language: English
• Subjects: Ion exchange resin; Separation; Spent SCR catalyst; Tungsten; Vanadium
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2023.139157

Vanadium (V) and tungsten (W) are essential metals for various industries, but separating them is challenging due to the molecular similarity of the two metal ions. A highly concentrated mixed solution of V and W is obtained from spent selective catalytic reduction (SCR) catalysts, but their complete recycling is impeded by the difficulty of separating V and W. In this study, we investigate the ion exchange resin (IXR) technique's effectiveness for separating V and W from the leaching solution of spent catalysts. We evaluated the performance of three IXRs: Lewatit MP800 (strong basic), MP62WS (medium basic), and TP260 (weak acidic) for the separation of V and W ions in the solution. Among these IXRs, MP800 exhibits V and W ion separation behavior at pH 14. It selectively adsorbs W ions, while V ions demonstrate low affinity for adsorption on MP800. The primary mechanism for the adsorption of V and W ions appears to be an ion exchange reaction on the quaternary ammonium group of MP800. Conversely, MP62WS, which adsorbs V and W ions through both ion exchange and chelation mechanisms, does not separate V and W ions effectively when the solution's pH is controlled. The adsorbed W ions on MP800 can be completely regenerated with 2 M NaCl solution through re-ion exchange. We also conducted dynamic column operations using a simulated spent catalyst leaching solution (V = 600 mg/L, W = 4000 mg/L) with MP800 at pH 14. The successful separation of V and W was achieved for up to 15 bed volumes (BV). Finally, we performed V and W separation using an actual spent catalyst leaching solution. MP800 displayed a notably high separation factor (αVW) of 19.59, highlighting its effectiveness in separating V and W. [Display omitted] •The separation of vanadium(V) and tungsten(W) was investigated by ion exchange technique.•The W ion is selectively adsorbed onto Lewatit MP800 at pH 14 but V ion remains in leachate.•The adsorption of V or W ions on MP800 at pH 14 is based on an ion exchange mechanism.•V and W can be completely separated from each other in a continuous column operation.•In an actual SCR leachate, MP800(pH 14) demonstrates the feasibility of separating W.