Understanding the reduction mechanism and coordination of tungsten ions in molten salt is one of the key factors to improve the electrolysis efficiency of tungsten carbide. In situ spectroscopy combined with simulation calculation is a strong analytical technique for characterizing chemical species and their behaviors in molten salts. The tungsten ion group was investigated by in situ high-temperature and room-temperature spectroscopy combined with density functional theory (DFT) calculations. For the described in situ spectroscopic studies, a new setup was used, which allowed the registration of UV–vis spectra of tungsten ions in cationic and anionic molten salt systems. The DFT calculation results proved useful for estimating the trend of experimental spectra. Through experimental and theoretical studies, the tungsten ion groups in various molten salt systems were identified, and the effect of cations and anions in molten salt systems onto tungsten ion group formation could be elucidated.
Yahui Zhao,Liwen Ma,Quan-Fu An,Xiaoali Xi,Zuoren Nie
Due to the nearly identical physical and chemical properties of tungsten (W) and molybdenum (Mo), the efficient recycling of W-Mo resources remains a significant research challenge. In this work, a W ion imprinted polymer (W-IIP) was proposed for a more efficient and environmentally friendly W-Mo separation process. W-IIP was prepared by a bulk polymerization method with 4-vinylpyridine as monomer, W(Ⅵ) as ion template, and ethylene glycol dimethacrylate as crosslinker. Characterization by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and thermogravimetry revealed that W-IIP possessed abundant pyridyl recognition sites, uniform particle structure, a large specific surface area, and good thermal stability. Through optimizing the adsorption conditions, the maximum separation coefficient β Mo W MAX reached 75, and an adsorption capacity Q W of 63.8 mg⋅g −1 was achieved at pH 4.5, a temperature of 75 ℃, and a time of 300 min. Based on the adsorption isotherms and kinetics fitting results, the adsorption process followed the pseudo-first-order kinetic model and the Langmuir model, and the adsorption of W was spontaneous monolayer surface adsorption. After five adsorption–desorption cycles, Q W remained at 92 %. The X-ray photoelectron spectroscopy characterization combined with the W-Mo-H 2 O thermodynamic diagram, suggested that the combination of the pyridine groups as recognition sites and the imprinted cavity of the W-IIP with tungstate may be the reason for the effective selective adsorption of W. Considering its excellent affinity and specific selectivity, W-IIP might evolve into a potential material for the separation of W and Mo although it faces limited recycling ability, cost implications and potential scalability constraints in the future. To address these limitations, future research could focus on developing new synthetic methods and optimizing the monomers to further enhance the overall performance of W-IIP.
危险品化学品经营许可证（带存储）