光化学分离水溶液中铂族金属元素的研究——Pd(Ⅱ)的光还原

    Photochemical Separation of Platinum Group Metals in Aqueous Solution——Photoreduction of Pd(Ⅱ)

    • 摘要: 采用光化学法将Na2PdCl4水溶液中的二价钯离子(Pd(Ⅱ))还原至钯单质,通过改变照射光波长、自由基清除剂种类、Cl-浓度、pH值等参数以获得光还原Pd(Ⅱ)的最佳条件。采用紫外-可见吸收光谱(UV-vis)和X射线光电子能谱(XPS)等表征手段分别对上清液和生成的沉淀进行表征。结果表明:使用光化学法能成功地还原出水溶液中的钯离子,提取率可达98.4%;相比之下,采用异丙醇作为自由基清除剂时能更有效地提取溶液中的钯元素。高浓度的Cl-抑制Pd(Ⅱ)的还原;适当提高pH值可以促进Pd(Ⅱ)的还原。此外,还验证了从Na2PdCl4和NdCl3混合溶液中光还原并分离Pd(Ⅱ)的可行性。

       

      Abstract: In present work, the photochemical method was proposed to reduce Pd(Ⅱ) ions in Na2PdCl4 aqueous solution, and the effects of various experimental parameters including the wavelength of light, radical scavengers, concentration of Cl- and pH values were studied. The supernatant and precipitation products have been characterized by the UV-vis spectra and XPS respectively. The results indicate that Pd(Ⅱ) ions in aqueous solution can be extracted by the photoreduction method by a ratio of 98.4%, and the generation of Pd atoms is more efficient in the presence of 2-propanol than ethanol, methanol or tertiary butanol. High concentration Cl- will suppress the reduction of Pd(Ⅱ), and high pH value can enhance the reduction of Pd(Ⅱ). In addition, the extraction of palladium metal from the mixed solution of Na2PdCl4 and NdCl3 was also demonstrated.

       

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