Preparation of sulfur-containing functional group-modified resin and its tungsten‑molybdenum adsorption and separation performance with application to waste-alloy leachate

Since W and Mo are strategic metals in China, the efficient, clean, and value-added utilization of secondary W and Mo resources is important. Ion-exchange methods using resins for the adsorption of Mo after sulfidation can effectively separate W and Mo, but these methods cause sulfide pollution. In this study, the macroporous anion exchange resin D301, which consists of a styrene-divinylbenzene copolymer matrix with tertiary amine groups, was modified by ethyl (methylthio) acetate (EA) of molecular formula C₅H₁₀O₂S to form resin EA-D301. This resin has the following properties: (i) enhanced the efficiency of W and Mo adsorption and separation, (ii) exhibited a dense structure and well-developed pores, (iii) maximum adsorption capacity (Q_W) of 1062 mg/g for W, and (iv) maximum separation factor (${\beta }_{\mathrm{Mo}}^W$) of 6.95 at pH 7.5 and 25 °C in a WMo solution with equal metal concentrations of 0.05 mol/L. The adsorption of both W and Mo by EA-D301 was hardly affected by other anions, and Q_W remained as high as 908 mg/g after ten adsorption-desorption cycles, indicating good stability. The adsorption mechanism was an ion-exchange reaction followed by coordination reactions. When EA-D301 was used to treat actual WMo waste alloy leachate, a Q_W of 647 mg/g and a ${\beta }_{\mathrm{Mo}}^W$ of 4.03 were achieved, demonstrating good performance in industrial applications. The EA-D301 resin is a promising W adsorbent with advantages such as simple synthesis, high adsorption capacity, and environmental friendliness. This resin provides an effective way to extract W and separate W and Mo from various resources.