Preparation and Characterization of a High-Efficient Potassium Adsorbent H₈Nb₂₂O₅₉·8H₂O

Abstract:

The adsorbent of H₈Nb₂₂O₅₉·8H₂O and the precursor of Rb₈Nb₂₂O₅₉ were characterized by X-ray diffraction (XRD), Thermogravimetric and differential scanning calorimetry (TG-DSC), and scanning electron microscope (SEM). The ion-exchange properties of H₈Nb₂₂O₅₉·8H₂O for Na⁺ and K⁺ were also investigated, including the saturation adsorptive capacity, distribution coefficients and separation factor. The results show that the crystallinity of Rb₈Nb₂₂O₅₉ was affected by the calcination temperature. The structure of Rb₈Nb₂₂O₅₉ was not changed when Rb⁺ was extracted from Rb₈Nb₂₂O₅₉, indicating that this process was topotactical. The calcination temperature and pH value had a significant influence on the ion-exchange capacities of H₈Nb₂₂O₅₉·8H₂O for Na⁺ and K⁺. Specifically, the uptake amouts of Na⁺ and K⁺ by H₈Nb₂₂O₅₉·8H₂O increased with the calcination temperature, while the distribution coefficients of Na⁺ and K⁺ for H₈Nb₂₂O₅₉·8H₂O increased with the pH value. Moreover, the separation factors for K⁺ was larger than that for Na⁺ and it increased with the increase of calcination temperature. Overall, the improvement of the crystallinity of H₈Nb₂₂O₅₉·8H₂O was beneficial to its selectivity for K⁺.

• Periodical: Advanced Materials Research (Volumes 1079-1080)
• Pages: 46-49
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1079-1080.46
• Online since: December 2014
• Authors: Chang Wang*, Peng Fei Cao, Xiang Long Zhang
• Keywords: Adsorbent, Ion Exchange, K⁺, Na⁺, Rb₈Nb₂₂O₅₉

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